JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year COMPUTATIONAL STATISTICS Previous Question Paper (March - 2022 - R18)

B.Tech | II Year | I Semester | R18 | March - 2022

Answer PaperPaper Code: 153CEMaximum Marks: 75Time: 3 Hours

Answer any five questions. All questions carry equal marks.

Main

115 marks
a

Solve

7x ≡ 4 (mod 11)

7 marks

Answer

To solve the linear congruence 7x ≡ 4 (mod 11), we need to find the modular multiplicative inverse of 7 modulo 11. We look for an integer y such that 7y ≡ 1 (mod 11).

Testing values for y:

  • 7(1) = 7 ≡ 7 (mod 11)
  • 7(2) = 14 ≡ 3 (mod 11)
  • 7(3) = 21 ≡ 10 (mod 11)
  • 7(8) = 56 = 5(11) + 1 ≡ 1 (mod 11)

The modular inverse of 7 modulo 11 is 8. Multiplying both sides of the original congruence by 8:

8(7x) ≡ 8(4) (mod 11)
56x ≡ 32 (mod 11)

Since 56 ≡ 1 (mod 11) and 32 ≡ 10 (mod 11), we get:

x ≡ 10 (mod 11)
b

Find x if possible such that

x ≡ 2 (mod 7)
x ≡ 3 (mod 10)

8 marks

Answer

We have the system of congruences:

x ≡ 2 (mod 7)
x ≡ 3 (mod 10)

From the first congruence, we can write x = 7k + 2 for some integer k. Substituting this into the second congruence:

7k + 2 ≡ 3 (mod 10)
7k ≡ 1 (mod 10)

To solve for k, we find the inverse of 7 modulo 10. By inspection, 7 × 3 = 21 ≡ 1 (mod 10). Multiplying both sides by 3:

3(7k) ≡ 3(1) (mod 10)
k ≡ 3 (mod 10)

Thus, k = 10m + 3 for some integer m. Substituting this back into the expression for x:

x = 7(10m + 3) + 2
x = 70m + 21 + 2
x = 70m + 23

Therefore, the solution is x ≡ 23 (mod 70).

215 marks
a

For the continuous probability function

F(x) = K x e-x/2, x ≥ 0
. Find i) K ii) Mean iii) variance.

6 marks

Answer

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b

Two dice are thrown 5 times. If getting a doublet is a success. Find the probability that getting the success i) At least once. ii) Two times.

9 marks

Answer

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3

200 digits were chosen at random from a set of tables. The frequencies of the digits were:

Digits0123456789
Frequency18192321162522202115

Use

χ2
test to assess the correctness of hypothesis that the digits were distributed in equal numbers in the table.

15 marks

Answer

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415 marks
a

The standard deviation of heights of students is 10 cms. A sample of 196 students was taken and the mean is 170 cms. Is this sample has been taken from a large population whose mean is 175 cms.

7 marks

Answer

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b

A simple sample of heights of 6400 Englishmen has a mean of 67.85 and Standard deviation of 2.56 inches. While a simple sample of heights of 1600 Australian has a mean of 68.55 and a S.D. of 2.52 inches Test the significance between the two mean.

8 marks

Answer

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5

There are three stores of groceries. There will be a shift from one store to another. A study was made on January first and it was found that 1/4 was shopped at store 1, 1/3 at 2 and 5/12 at 3. Every month store 1 retain 90% of their customers and 10% transformed to store 2. Store 2 retain 5% of their customers and 85% transformed to store and 10% to store 3. Store 3 retain 40% of their customers and 50% transformed to store 1 and 10% to store 2.

a) What proportion of customers retain by Feb 1st and March 1st

b) Find the long run proportions.

15 marks

Answer

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615 marks
a

Solve

x ≡ 3 (mod 12)
x ≡ 0 (mod 6)

7 marks

Answer

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b

Solve

x ≡ 3 (mod 5)
x ≡ 1 (mod 7)
x ≡ 6 (mod 8)

8 marks

Answer

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7

Calculate the coefficient of correlation and the two lines of regression between the two variables x and y.

x141617181920212223
y847870756667625860
15 marks

Answer

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815 marks
a

Find whether the following is a regular transition matrix

P = [[0, 0.5, 0.5], [0.5, 0, 0.5], [0.5, 0.5, 0]]

7 marks

Answer

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b

Find the equilibrium vector of

[[0.25, 0.75], [0.5, 0.5]]

8 marks

Answer

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About this paper

This page contains the solved question paper with answers of COMPUTATIONAL STATISTICS from JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD for B.Tech CSBS II Year I Semester, March - 2022, R18.

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