Wednesday, 21 August 2019

Some Integrals which can not be found

Some Integrals which cannot be found

1) sinx/x  dx
2)  ∫ cosx /x  dx
3)  ∫ dx/log x
4) ∫ √(1 - k²sin²x) dx
5)  ∫ √(sinx) dx
6)  ∫ sin(x²) dx
7)  ∫ cos(x²) dx
8)  ∫ xtan x  dx
9)  ∫ ₑ-x² dx
10)  ∫ ₑx² dx
11)  ∫ x²/(1+x⁵) dx
12) ³√(1+x²) dx
13)  ∫ √(1+x³) dx

Monday, 5 August 2019

TIME SERIES ANALYSIS

TIME SERIES ANALYSIS


                TIME SERIES

A) Find the moving average of

1) 1, 0, -1, 0, 1,0, -1, 0,1    4yrs..

2) Year: 1   2   3   4   5   6   7    8   9  Sales:  36 43 43 34 44 54 34 24 15

4 years centred moving average. 


3) 5 yrly moving average:
Year:  1    2   3    4    5  6   7  8  9 10
Sales:32 17 57  92  2  5 10 27 5 31 


4) 3 year moving average:
Year:     1   2   3   4   5   6     7

Values: 2   4   5   7   8  10  13 


5) Using 3-year moving average method determine the trend and short-term fluctuations::
Year:      1     2     3    4    5    6     7
Values: 21   30  40  25  40  55  70 


6) Find the 3-year weighted moving average with weights 1,4,1 for the following series:
Year :    1    2   3     4    5    6    7
Values: 2    5   6     5    8    3    3 


7) Year  production ('0000 tonnes)
    1995          506
    1996          620
    1997         1036
    1998          673
    1999          588
    2000          699
    2001        1116
    2002          783
    2003          663
    2004          773
    2005        1189
Find the 4 years moving average.

B) Use the method of least square 

1) Year: 01     02    03    04     05
Prod:     10     12      8    10     14
Use the method of least squares to fit a straight line to the data. Also find the trend values for different years.                10.8+ 0.6x; 9.6, 10.2, 10.8, 11.4, 12.0


2) Year:   00    01   02       03      04

Insured: 11.3  13   9.7    10.6   10.7

Find the insuranced people in 1997?              Y=11.06 - 0.4x; 8.18.


3) Yr: 1991 92   93   94   95   96   97

Sales:125 128 133 135 140 141 143

Find the trend values:.      Y=135+ 3.107x, 125.679, 128.786, 131.893, 135, 138.107, 141.214, 144.321.


4) Yr: 1980  81 82  83  84 85 1986

Profit: 60    72  75  65  80 85   95

Estimate the profit for 1987.       Y= 76+ 4.857x; 95.428 lacs.


5) Obtain the trend Equation and tabulate against each year after estimation of the trend and short-term fluctuations.

   Year                   Value

   1997                   380

   1998                   400

   1999                    650

   2000                    720

   2001                    690

   2002                    620

   2003                    670

   2004                    950

   2005                  1040          y= 680 + 70.5x; -18.0, -68.5, 111.0, 110.5, 10.0, -130.5, - 151.0, 58.5, 78.0.


6) Determine the equation of a straight line which best fits the following data:

 year:.  01     02     03     04      05

 Sales: 35     56     79     80      40 

Compute the trend values for all the years from 2001 to 2005.        Y= 58 + 3.4x, 51.2, 54.6, 58.0, 61.4, 64.8


7) Fit a suitable straight line to the following data by the method of least squares and estimate the percentage of insured people in 1997:

Year: 1989  1990 1991 1992 1993 

Ins:    11.3   13.0   9.7   10.6  10.7 

  Y= 11.06- 0.36x, 8.9 


8) The following table gives the annual profits(in thousand ₹) in a factory:

Year            profit ('000 ₹)

1991            60

1992            72

1993            75 

1994            65 

1995            80 

1996            85 

1997            90

a) fit a straight line trend by the method of least squares.   Y=75.29 + 4.32x

b) find the gradient of the fitted trend line.                                      4.32

c) calculate the projected profit for 1998.                                       92570


C) 

1) Year: 1994   95   96   97  98  99

    Sale :    12    15   17   22  24  30

Estimate the volume of sale for 2000.         Y=20+1.74x; 32.2 units.


2) yr: 1997   98   99   00    01   02

Price: 250  207  228 240 281 300

Find the trend value of 2004:      y= 266.33 + 13.49x; 387.74.


3) Year.               Value

       1996                 380

       1997                 400

       1998                 650

       1999                 720

        2000                690

        2001                600

        2002                870

        2003                930

Estimate the value of 2005.         Y= 655+ 35.83x referred to midpoint of 1983-84 as origin and unit of x as 6 months; 1049.13.


4) Fit a straight line trend equation by the method of least squares and estimate the trend values:

Year            values

1991            80

1992            90

1993            92

1994            83 

1995            95

1996            99

1997            92 

1998           104 

 Y= 91.75 + 1.25x, 83, 85.5, 88, 90.5, 93, 95.5, 98, 100.5


5) The weight of a calf taken at weekly intervals are given:

Age in weeks(x)       Weight (y)

1                                  52.5 

2                                  58.7 

3                                  65 

4                                  70.2 

5                                  75.4 

6                                  81.1 

7                                  87.2 

8                                  95.5 

9                                102.2 

10                              108.4     Fit a straight line using the method of least squares and estimate the average rate of growth per week.     Y= 45.73 + 6.162x, 6.162.



D) 

1) year:  2005  10   15  20  25  2030

   Profit:   10     13  15   20  22    28

Find the profit for 2035.           Y= 18.1.743x; x=2.5yrs; 30.20 lakh.


2) Yr: 1995    97    99   2001   2003

Sales: 18       21    23     27       16

Estimate the sales in 2000, and 2005.      Y= 21+ 0.1x; 21000, 21600

 

E) Find the Seasonal indices and seasonal Index of following using the method of average:

1) Year:            Quarters

                   I         II         III       IV

2003        37       38       37      40

2004        41       34       25      31

2005        35       37       35      41

1.75, 0.42, -3.59, 1.42


2) Year:            Quarters

                   I       II       III    IV

2002        39     21     52   81

2003        45     23     63   76

2004        44     26     69   75

2005        53     23     64   84 

   86.4, 44.4, 118.4, 150.8


3) year     I          II       III         IV 

    2001   72       68     80        70

    2002   76       70     82        74 

    2003   74       66     84        80 

    2004   76       74     84        78 

    2005   78       74     86        82 

 96.4, 92.1, 106.9 100.5 


4)  Year     1st      2nd      3rd       4th

    2002    16.00  13.50  14.70  17.00

    2003    15.90  12.20  15.60 18.10 

    2004    16.30  11.90  16.90 19.20 

    2005    17.10  13.20  15.00 18.70 

   0.77, -3.31, 0.11, 2.43 


5) Year       I         II        III         IV 

    2001     71      68      79        71

    2002     76      69      82       74 

    2003     74      66      84       80 

    2004     76      73      84       78 

    2005     78      74      86       82 

 -1.25, -6.25, 6.75, 0.75


6) year.     I       II        III          IV 

    2000    75    60      54        59 

    2001    86    65      63        80 

    2002    90    72      66        85 

    2003  100   78      72         93 

    117.20, 91.82, 85.14, 105.84



F) Find the seasonal Indices by the method of moving averages from the following:

1) Year:            Quarters
                   I        II        III      IV
2002        97     100    106   110
2003        88      93       96    101
2004        76      79       83     88
2005        94      98      103   106

  10.12,0.13, -14.08, 3.83


2) Year:            Quarters
                   I       II       III    IV
1990        34     32     31   36
1991        37     34     33   41
1992        43     40     38   48

  33.625, 34.25, 34.75, 35.625, 37, 38.5, 39.875, 41.375


3) Year:            Quarters

                   I       II       III    IV
2002       101   93     79    98
2003       106   96     83   103
2004       110  101    88   106 

110.9,99.9, 84.9, 104.3


4) Year:            Quarters

                   I       II       III    IV

2002         65    58     56    61

2003         58    63     63    67

2004         70    59     56   52 

2005         60    55     51   58 

      2.83, - 0.50, -2.17, -0.17 


5) Year:            Quarters

                   I        II       III      IV
2002         75     60     54     59

2003         86     65     63     80

2004         90     72     66     85

2005        100    78    72     93

122.36, 92.43, 84.70, 100.51


 

G) 1) A company estimates it's average monthly sales in a particular year to be ₹200000. The seasonal Indices (SI) of the sales data are as follows:
Month             SI
Jan                  76
Feb                  77
Mar                 98
Apr                 128
May                137
June.              122


2) A company estimates it's average monthly sales in a particular year to be ₹2000000. The seasonal Indices (SI) of the sales data are as follows:
Month             SI
Jan                  78
Feb                  75
Mar                 100
Apr                  126
May                 138
June.               121
July                  101
Aug                  104
Sept.                  99
Oct                    103
Nov                     80
Dec                     75 

Ignoring the possibile existence of a trend, use the above information to draw up a monthly sales budget for the company.                 15.6, 15.0, 20.0, 25.2, 27.6, 24.2, 20.2, 20.8, 19.8, 20.6, 16.0, 15.0

3) A company estimates its average monthly sales in a particular year to be ₹2000000. The seasonal Indices (SI) of the sales data are as follows:

Month             SI

Jan                  76

Feb                  77

Mar                 98

Apr                 128

May                137

June.              122

July                101

Aug                104

Sept.               100

Oct                  102

Nov                   82

Dec                   73 

Using this information, draw up a monthly sales budget for the company. (Assume that there is no trend)                152000, 154000, 196000, 256000, 274000, 244000, 202000, 208000, 200000, 204000, 164000, 146000.



Saturday, 3 August 2019

Math test(1) CLASS 12

1) a) Find the inverse of.  2     -2
                                              4      3
                                                       (2)
b) If f: N -> R be a function defined
    as f(x) = 4x²+12x+15, show that
    f: N -> S, where S is the range of f
    is invertible.
   Find the inverse of f.              (2)

c) eˣ+eʸ=eˣ⁺ʸ prove y₁= - eʸ⁻ˣ.  (2)

d) prove.                                      (2)
tan⁻¹ 1/2+ tan⁻¹1/5 + tan⁻¹1/8=π/4

e)Evaluate limₓ-₀ tan8x/sin 2x.  (2)

2) using the properties of Determinant find
1    a      a²-bc
1     b     b²-ca
1     c     c²-ab                              (4)

3)  show sin⁻¹12/13+cos⁻¹4/5 +
      tan⁻¹63/16 =π                     (4)              

4) If eʸ(x +1) =1 show y₂ =( y₁)²   (4)

5) i) ∫ x²eᵃˣ dx.    ii) ∫ xlogx dx.    OR

        ∫ dx/(x³+x²+x+1)              (4)

6) Find the point on the curve
     y= x³-11x+5 at which the
     equation of the tangent is
     y= x -11                               ( 4)
                         OR
If f(x) = (4x+3)/(6x -4) , x≠2/3. what is the inverse of f.

7) If A= 2  -3   5
             3    2  -4
             1    1  -2 , find A⁻¹ . Using A⁻¹, solve the following system of equations. 2x-3y+5z=16, 3x+2y-4z=-4, x+y-2z=-3            (6)  

                       OR

If A = 1       2      3
          2       3      1
         -1       1      1    using elementary transfirmation, find A⁻¹ and verify A⁻¹A = I = AA⁻¹.

8) Show that the semi-vertical angle of the cone of maximum volume and of given slant height is tan⁻¹√2
                     OR                          (6)
Find the area of the great rectangle that can be inscribed in the ellipse
x²/a² + y²/b² = 1.

9) ∫ (tanθ +tan³θ)/(1+tan³θ)dθ. (6)

10) a) The demand functiin of a
      monopolist is given by
      p= 100 -x-x².
     find
  i) the revenue function.
ii) marginal revenue function.    (2)

11) A furniture dealer deals in only two items: tables and chairs. He has Rs20000 to invest and a space to store at most 80 pieces. A table costs him Rs500 and a chair costs him Rs200. He can sell a table for Rs950 and a chair for Rs280. Assume that he can sell all the items that he buys. Formulate this problem as an LPP so that he can maximize his profit.                   (6)

SUBMULTIPLE ANGLES

SUBMULTIPLE ANGLE 

+--++++++----------------

A)Prove

1) cot(x/2) -tan(x/2) = 2cotx

2) cos⁴(x/2) - sin⁴(x/2) = cos x

3) (1+cosθ)/sinθ = cot(θ/2)

4) (sinα/2 ⊕ cosα/2)² = 1⊕ sinα

5) sin2α/(1-cos2α).(1-cosα)/cosα
       = tanα/2

6) (1+sinα -cosα)/(1+sinα +cosα)
          = tan(α/2)

7) 2cscα = tan(α/2) + cot(α/2)

8) sin2θ/(1+cos2θ). cosθ/ 
                                         (1+cos2θ) 
                                          = tan(θ/2)

9) (tanx+secx -1)/(tanx -secx +1)
                    =  tan(π/4  +x/2)

10) secα+tanα =tan(π/4+ α/2)

11) secα - tanα = tan(π/4  -α/2)

12) tan(π/4 +α/2) 
                     = √{(1+sinα)/(1-sinα)
                     = secα -tanα 

13) tan(α+β)/2 + tan(α-β)/2 =
                      2sinα/(cosα +cosβ)

14) cotx = ½(cot(x/2) - tan(x/2))

15) 8sin⁴(α/2) - 8 sin²(α/2)+1
                                           = cos2α

16){sinα/2-√(1+sinα)}/
                             {cosα/2-√(1+sinα)
                                        = cot(α/2)

17) (2sinθ -sin2θ)/(2sinθ +sin2θ)
                     = tan²(θ/2)

18) (1+tan(α/2))/(1-tan(α/2)) =
                                  (1+sinα)/cosα

19) sinα =2tan(α/2)/(1+tan(α/2))

20) cosα + cosβ)²+(sinα +sinβ)² =
                                      4cos²(α-β)/2

21) 2cos(π/6)=√[2+{√2+√(2)}]

22) tan6 tan42 tan66 tan78 =1

23) sin(15/2) =√6 - √3 + √2 -2

24) 2sinx/2= ⊕√(1+sinx) ⊕
                                          √(1 -sinx)
B) Evaluate

1) sin²72 - cos²30

2) cosπ/5 + cos 3π/5

3) sin 45/2

4) tan 44/2

5) sin15

6) cos 15

7) sin 105

8) 4cos9

9) sin54 + cos72

10) sin18 + cos 36

11) sin²36 + cos² 18

12) cos² 66 - sin² 6

13) cos²48 - sin²12

14) 8cos²20 - 6 cos20

15) 3sin40 - 4 sin³ 40

16) sin²24 - sin²6

C) If tan(α/2) = √{(1-e)/(1+e)} tan(α/2)
then show cosα= (cosα -e)/
                                            (1-ecosα)
D) tanα = sinαsinβ/(cosα+cosβ) then show one of the values of tan(α/2) is 
tan(α/2) tan(β/2)

E) If sinα +sinβ =a and cosα+cosβ=b
then find the value if cos(α+β)

F) If A= 320 prove
 tanA/2={-1 + √(tan²A)}/tanA


Friday, 2 August 2019

MULTIPLE ANGLES

FORMULAE:


1) sin 2x= 2sin x cos x  


2) Sin 3x = 3 sin x - 4 sin³x


3) Cos 2x = cos²x - sin²x

                  = 2 cos²x - 1

                  = 1 - 2 sin²x

                  = (1- tan²x)/(1+ tan²x)


4) 1 + cos 2x = 2 cos²x OR

             Cos x= ± √{(1+ cos 2x)/2}


5) 1 - cos 2x= 2 sin²x OR 

             Cos x= ± √{(1- cos 2x)/2} 


6) Cos 3x = 4 cos²x - 3 cos x


7) Tan x= (1- cos 2x)/sin 2x

              = Sin 2x/(1+ cos 2x)

             =± √{(1- cos 2x)/(1+ cos 2x)


8) Tan 2x = 2 tanx/(1- tan²x)


9) tan 3x=(3tan x -tan³x)/(1-3 tan²x)


10) sin18°=(√5 -1)/4=cos72°= sin π/10


11) cos 36°= (√5+2)/4= sin54°= cos π/5


12) sin15°= (√3-1)/2√2 = cos75°= sin π/2


13) cos15°= (√3+1)/2√2 = sin75°= cos π/2


14) tan π/12 = 2 -√3 =(√3-1)/(√3+1) = cot 5π/12


15) tan 5π/12 = 2 + √3 =(√3-1)/(√3+1) = cot π/12


16) tan 225°= √2 - 1 = cot 67.5°= cot 3π/8 = tan π/8


17) tan 67.5°= √2+ 1 = cot 22.5°


 ========================      


EXERCISE -1

___________

1) Find Sin 2θ, cos2θ, tan2θ if 

a) cosθ=⅗.          24/25, -7/25, -24/7

b) sinθ=⅘.          24/25, -7/25, -24/7

c) tanθ=½.                          4/5, 3/5, 2

d) if cosA=⅗ find Sin2A

e) if sinA=⅗ find tan3A

f) If cos2a =24/25 find tan3A


2) EXPRESS:

a) cos4A in terms of sinA.       1 - 8 sin²A + 8 sin⁴A

b) tan4A in terms of tanA.       (4 tanA - 4 tan⁴A)/(1+tan⁴A-6 tan²A)

c) sin4A in terms of tanA.     


3) Prove:

a) Sin2α/(1-cos2α)= cotα

b) sin2θ/(1+cos2θ) = tanθ

c) cotβ + tanβ = 2csc2β

d) 1+ tanα tan2α = sec2α

e) tan²α = (sec2α -1)/(sec2α +1)

f) sec²θ(1+sec2θ) = 2sec2θ

g) (cosα+sinα)/(cosα-sinα) = tan2α + sec2α

h) tanβ(1+sec2β)=tan2β

i) tan2α/tanα = 1+sec2α

j) (cotθ+tanθ)/(cotθ-tanθ)=sec2θ

k) 2/(cotα-tanα) = tan2α

l) {sinα - √(1+sin2α)}/{cosα-√(1+sin2α)= cotα

m) tan(π/4 + α)=(1+sin2α)/cos2α

n) cos²(α+π/4)+cos²(α-π/4)=1

o) {(1-tanθ)/(1+tanθ)}² = (1-sin2θ)/(1+sin2θ)

p) tan(45+α)- tan(45-α) =2tan2α

q) tan(45+α)+ tan(45-α) =2sec2α

r) sec(45+α)sec(45-α) = 2sec2α

s) 4cosβcos(2π/3 +β) cos(4π/3+β) = cos(3β)

t) tan(π/4 +α/2)= secα +tanα = √{(1+sinα)/(1-sinα)}

u) (cotθ-tanθ)/(1-2sin2θ) = secθ cosec 2θ

v) cot15 - tan15 = 2tan60

w) tan15 + cot15 =4

x) (2cosα+1)(2cosα -1)=2cos2α +1

y) cos⁴α - sin⁴α = cos2α

z) cos⁶β -sin⁶β = cos2β(1- ¼ sin² 2β)

A) (sin²α-sin²β)/(sinα cosα-sinβcosβ) = tan(α+β)

B) (1-cos2α+sin2α) /(1+cos2α+sin2α) = tanα

C) cos³xcos3x+sin³xsin3x=cos³2x

D) {(cosα+sinα)/(cosα-sinα)} -

{(cosα-sinα)/(cosα+sinα)}=2tan2α

E) (sinα+sin2α)/(1+cosα+cos2α) = tanα

F*) (sinα/cosα) (1-cos2α)/(1-cos4α) = tanα

G) (cos³α+sin³α)/(cosα +sinα) =1 -  ½ sin2α

H) 1/sin10  - √3/cos10 = 4

I) cotα/(cotα -cot3α)  = tanα/(tan3α - tanα))

J) 1/(tan3α-tanα)- 1/(cot3α -cotα) = cot2α

K) sin8β=8sinβcosβcos2βcos4β

L) cos5θ = 16cos⁵θ - 20cos³θ+ 5cosθ

M) sin5α=16sin⁵α-20sin³α+5sinα

N) cos(120-α)+cosα+cos(120+α)=0

O) cos²(α-120) +cos²α +cos²(α+12) = 3/2

P) tan4α=(4tanα-4tan³α)/(1-6 tan²α+tan⁴α)

Q) (2cos2ⁿθ+1)/(2cosθ+1)=
  (2cosθ-1)(2cos2θ-1)........ (2cos2ⁿ⁻¹θ-1)

R) tan2ⁿθ/tanθ = (1+sec2θ)(1+sec2²θ) ...(1+secⁿθ)

S) sin⁴α=⅜ - ½ cos2α +⅛ cos4α

T) cos⁸α+sin⁸α= 1-sin²2α+⅛ sin⁴2α

U) tan(π/4 +α)+tan(π/4 -α)  =2sec2α

V) cos³α (sin3α)/3 +sin³α(cos³α)/3= (sin4α)/4

W) cos4α - cos4β= (cosα-cosβ)
(cosα+cosβ)(cosα-sinβ(cosα+sinβ)

X) tanθ+ 2tan2θ +4tan4θ +8tan8θ= cotθ

Y) (2cos8α+1)/(2cosα +1) =
(2cosα-1)(2cos2α-1)(2cos4α-1)

Z) cos²(α-β) - sin²(α+β) = cos2αcos2β

a') 4(cos³7+sin³23) =3(cos7 +sin23)



EXERCISE-2

-------------------

1) if tanx =b/a, find acos2x+bsin2x

2) If cosx +sinx =√2 cosy show that tan2y =1

3) If sin²x = siny cosy then show cos2x = 2cos(π/4 + y)

4) If cos2a=x+1/x show  2cosa =(x³+ 1/x³)

5) If tan²x 2tanx tan2y = 
 tan²y+2tanytan2x  prove that each side =1 or tanx = ± tany

6) If tan²θ = 1+ 2 tan²α show cos2α = 1+ 2cos2θ

7) If 2 tanα = 3tanβ show  tan(α-β) =sin2β/(5 -cos2β)

8) If tan(α+β-θ)/tan(α-β+θ) =
tanθ/tanβ then show that either
sin(β-θ)=0  or sin2α+sin2β+sin2θ=0

9) If α and β are acute angles and cos2α = (3cos2α-1)/(3-cos2β) then show that tanα =√2 tanβ

10) If cosα = ½(a +1/a) show that
a)cos2θ= ½(a²+ 1/a²)
b) cos3θ= ½ (a³ +1/a³)

11) If tanα = sec2α, then prove that
sin2α = (1-tan⁴α)/(1+tan⁴α)

12) If csc2α+csc2β +csc2θ = 0 show that tanα + tanβ+ tanθ + cotα + cotβ + cotθ=0

13) If tan³x=2tan²y+1 then show that cos²2x + sin²y = 0

COMPOUND INTREST

COMPOUND INTEREST

1) Find the difference between Simple interest and compound interest on Rs5000 invested for 4 years at 5% p.a., compounded yearly.

2) What rate of interest p.a. does a person get who is paid at the rate of 5% CI payable half yearly.

3) In 2 years a sum of money double itself in  compound interest. Find the rate percentage

4) What principal will amount to Rs551.25 in 2 years at 5% compound interest ?

5) A sum becomes 1323 in 2 years at compound interest compounded yearly. Find the rate percentage.

5) If the population of a Town increases every year by 2% of the population at the beginning of that year, in how many years will the total increase of population be 10%

6) In how many years will the population of a village change from 2500 to 2601, if the rate of increase is 2% p.a ?

7) The difference between Simple and compound interest on a sum for 3 years at 5% p.a is Rs76.25. Find the sum.

8) The sum of 956 amounts to Rs1099.40 in 3 years, at simple interest What sum of money invested at compound interest, payable yearly, will amount to TmRs1481.97 in 3 years, the rate of interest p.a. in both the cases being the same ?

9) A sum of money invested at compound interest, payable yearly, amounts to Rs 2704 at the end of the second year and to Rs2812.16 at the end of the third year. Find the rate of interest and the sum.

10) The difference between the Simple and compound interest at the same rate for 2 years on a certain amount is 1/100th of the amount. Find the rate of interest.

11) A man deposits Rs5000 in a Savings account which pays compound interest at the rate of 4.5% for the first 2 years and at the rate of 5% for 1 year. Find the amount after 3 years.

12) Find the compound interest on Rs 6950 for 3 years, if interest is payable half-yearly, the rate for the first two years being 6% and for the third year 9%p.a.

13) A sum of money invested at compound interest amount to Rs10816 at the end of the second year and to Rs11248 at the end of third year, find the rate of interest and the sum invested.

14) A sum of money invested at compound interest amounts to Rs 17640 at the end of the second year and to Rs18522 at the end of third year. Find the sum originally invested and the rate of interest.

15) A sum of money is lent at 8% p.a compound interest. If the interest for the second year exceeds that for the first year by Rs32, find the original principal.

16) What is the present value of a reversion to Rs3000 after 7/2 years reckoning 4% C. I payable yearly.

17) A loan earns interest at a certain rate(compound) percent p.a. Four years ago amount was Rs81; now it is Rs144. What will the amount be two years hence ?