Probability And Statistics - Study Mode

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[#81] The box 1 contains chips numbered 3, 6, 9, 12 and 15. The box 2 contains chips numbered 6, 11, 16, 21 and 26. Two chips, one from each box, are drawn at random. The numbers written on these chips are multiplied. The probability for the product to be an even number is

(A) $$frac{6}{{25}}$$

(B) $$frac{2}{5}$$

(C) $$frac{3}{5}$$

(D) $$frac{{19}}{{25}}$$

Correct Answer

(D) $$frac{{19}}{{25}}$$

[#82] For random variable x($$ - infty $$ xa0< x < $$infty $$) following normal distribution, the mean is μ = 100. If probability is P = α for x ≥ 110. Then probability of x lying between 90 and 110 i.e., P(90 ≤ x ≤ 110) is equal to

(A) 1 - 2α

(B) 1 - α

(C) $$1 - frac{alpha }{2}$$

(D) 2α

Correct Answer

(A) 1 - 2α

[#83] A box contains 5 black and 5 red balls. Two balls are randomly picked one after another from the box, without replacement. The probability for both balls being red is

(A) $$frac{1}{{90}}$$

(B) $$frac{1}{2}$$

(C) $$frac{{19}}{{90}}$$

(D) $$frac{2}{9}$$

Correct Answer

(D) $$frac{2}{9}$$

[#84] In the following table, x is a discrete random variable and p(x) is the probability density. The standard deviation of x is x 1 2 3 p(x) 0.3 0.6 0.1

(A) 0.18

(B) 0.36

(C) 0.54

(D) 0.6

Correct Answer

(D) 0.6

[#85] Three companies X, Y and Z supply computers to a university. The percentage of computers supplied by them and the probability of those being defective are tabulated below: Company % of computer Probability of being supplied defective X 60% 0.01 Y 30% 0.02 Z 10% 0.03 Given that a computer is defective, the probability that it was supplied by Y is

(A) 0.1

(B) 0.2

(C) 0.3

(D) 0.4

Correct Answer

(D) 0.4