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Home > Computer Science > Numerical and Statistical Computing
 
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Numerical and Statistical Computing
 

Question 1.

(a) Write FORTRAN 77 and FORTRAN 90 expressions for the following

Ans.

EQUIVALENT FORTRAN EXPRESSION

= ((a * X + b ) / c) + (( 1. - EXP(-ALPHA * SQRT(X))) /(1. + X * EXP(-ABS(X)))) + (ALPHA * COS(OMEGA * T +PHI) / SQRT (ALPHA**2 + OMEGA**2))
(b) Evaluate the following FORTRAN 77 expressions:

(i) 2 * * 3 * * 2 * 2 + 4/3 * 2,

(ii) (a/2) (a+2.5)/b,
a = 2.5 and b = 3.5,

(iii) 4 + 7 .LT. 9 .OR. 8 .GT. 4 + 7

Ans.

Solution 1(b)(i).

2**3**2*2+4/3*2
=2^3^2*2+4/3*2
=2^9*2+8/3
=2^10+2.6667
=1024+2.6667
=1026.6667 =1026.7

solution 1(b)(ii).

(a/2)(a+2.5)/b
=(2.5/2)(2.5+2.5)/3.5
=(1.25)(5)/3.5
=(1.25)(1.4286)
=2.6786

solution 1(b)(iii).

(4 + 7 .LT. 9 .OR. 8 .GT. 4 + 7)
PERFORMING THE RELATIONAL COMARISIONS (.LT. , .GT. )LEFT TO RIGHT
(false .OR. 8 .GT. 4 + 7)
From the hierarchy table , when both inputs are false, OR operator is false
(false .OR. false ) gives false

Question 2.

(a) The mean annual salary paid to all employees of a company was Rs. 5000/-. The mean annual salaries paid to male and female employees were Rs. 5200/- and Rs. 4200/- respectively. Determine the percentage of males and females employed by the company.

x1=5200, x2=4200, x=5000

x = n1x1 + n2x2
n1+n2

5000 = 5200n1 + 4200n2
n1+n2

5000(n1 + n2) = 5200n1 + 4200n2

5000n2 - 4200n2 = 5200n1 - 5000n1

8000n2=2000n1

8n2=2n1

n1/n2 = 8/2 =4/1

Therefore ,

percentage of male employee in the company =4/4+1*100=400/5=80%

percentage of female employee in the company =1/4+1*100=100/5=20%
(b) Three urns of the same appearance have the following proportion of balls

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First urn: 2 black 1 white
Second urn: 1 black 2 white
Third urn: 2 black 2 white

(c) Calculate the correlation coefficient for the following heights (in inches) of fathers (x) and their sons.

X: 65 66 67 67 68 69 70 72
Y: 67 68 65 68 72 72 69 71

Ans.

X y X2 Y2 xy
65 67 4225 4489 4355
66 68 4356 4624 4488
67 65 4489 4225 4355
67 68 4489 4624 4556
68 72 4624 5184 4896
69 72 4761 5184 4968
70 69 4900 4761 4830
72 71 5184 5041 5112

 

åx=544 åy=552 åX2=37028 åY2=38132 åxy= 37560

 

nåxy = 300480 n=8
åx åy = 300288 n åxy - åx åy= 300480 – 300288 = 192
n åX2 = 296224 n (åX2) -(åx)2=296224 – 295936 = 288
(åx)2 = 295936 n (åY2) - (åy)2 = 305056 – 304704 = 352
n åY2= 305056

{nåX2- (åx)2} {n åY2- (åy)2} = 288 * 352


= 101376
 

(åy)2= 304704

√ ({n åX2- (åx)2} {n åY2- (åy)2}) =  318.396


r = (n åxy - åx åy)

( {n åx2 -(åx)2} {n*åy2-(åy)2} )

= 192
318.396

= 0.603023

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