Probability - Study Mode

[#106] For a random variable X, E(X) is
Correct Answer

(C) Arithmetic Mean (AM)

Explanation

Solution: Arithmetic Mean (AM)

[#107] Probability distribution of a random variable is also known as
Correct Answer

(B) Probability Function

Explanation

Solution: Probability Function

[#108] There are 20 balls in a bag which are numbered 1, 2, 3 . . . . . 20. Find the probability that the number marked on the ball taken out of the bag is divisible by 3 or 5.
Correct Answer

(B) $$frac{9}{{20}}$$

Explanation

Solution: Number divisible by 3 = 6 Number divisible by 5 = 4 Number divisible by 3 or 5 = 1 Total number = 6 + 4 - 1 = 9 Probability = $$frac{9}{{20}}$$

[#109] What is the probability that a two digit number is not a prime number when a number is chosen at random?
Correct Answer

(B) $$frac{{23}}{{30}}$$

Explanation

Solution: Two digit number = 10 . . . . . 99 = 90 number Prime number between 1 to 100 = 25 Prime number between 1 to 10 = 2, 3, 5, 7 = 4 Prime number between 1 to 99 = 25 - 4 = 21 $${ ext{Probability}} = frac{{90 - 21}}{{90}} = frac{{69}}{{90}} = frac{{23}}{{30}}$$

[#110] A letter of English alphabet is chosen at random, Probability of getting a vowel is-
Correct Answer

(A) $$frac{5}{{26}}$$

Explanation

Solution: $${ ext{P}}left( { ext{V}}
ight) = frac{5}{{26}}$$