Test: Probability- 2 - JEE MCQ

Total = 1400, therefore n(S) = 1400 Let A = event of getting easy question B = event of getting multiple choice question.

Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4

Let X be a random variable assuming values x1, x2,....,xn with probabilities p1, p2, ...,pn, respectively such that . If E is the expectation, mean of X is denoted by μμ, variance denoted by σ2, is defined as : σ2=E(X – μ)²

p = probability of success = 3/6 = ½ . q = probability of failure = 1 – p = 1 – ½ = ½ . let x be the number of successes , then x has the binomial distribution with : n = 6 , p = ½ , q = ½ 
 P(atmost 5 successes ) = P ( x ≤ 5 ) = 1 - P(x > 5) = 1 – P(x = 6) 

S = {(3,1), (3,2), (3,3), (3,4), (3,5), (3,6), (6,1), (6,2), (6,3), (6,4), (6,5), (6,6), (1,H), (2,H), (4,H), (5,H), (1,T), (2,T), (4,T), (5,T)} Let A = event that coin shows a tail. i.e. A = {(1,T), (2,T), (4,T), (5,T)} and B = event that atleast one die shows 3. B = {(3,1), (3,2), (3,3), (3,4), (3,5), (3,6),(6,3)}

Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4 P(A/B)=P(A)=0.3.

A random variable X taking values 0, 1, 2, ..., n is said to have a binomial distribution with parameters n and p, if its probability distribution is given by : 

When a die is tossed , then the doublets are {(1,1),(2,2),(3,3),(4,4),(5,5),(6,6)}. Therefore, p   . Let x be the number of successes , then x has the binomial distribution with : n = 4 , p = 1/6 , q = 5/6   P (2 successes) = P (x

We have , 
P(E) = 0.6, P(F) = 0.3 and P(E ∩ F) = 0.2, then , 

Let A and B be independent events with P (A) = 0.3 and P(B) = 0.4. P(B/A)=P(B)=0.4

Here , probability of getting a spade from a deck of 52 cards = 13/52 = ¼ . p = ¼ , q = ¾ . let , x is the number of spades , then x has the binomial distribution with n = 5 , p = ¼ , q = ¾ . P( all 5 cards are spades)= P (x = 5) = 

Since A and B are independent events .not A and not B are also independent events .

An urn contains 5 red and 2 black balls. Two balls are randomly drawn. Let X represent the number of black balls.therefore the possible values of X = 0 , 1 ,2 . Yes , X is a random variable.

Here , probability of getting a spade from a deck of 52 cards = 13/52 = ¼ . p = ¼ , q = ¾ . let , x is the number of spades , then x has the binomial distribution with n = 5 , p = ¼ , q = ¾ . P( only 3 cards are spades) = P (x = 3)

If E and F are independent, then P (E ∩ F) = P (E) P (F).

If A and B are two events such that A ⊂ B and P(B) ≠ 0, then , P(A|B) ≥ P(A).

Let X represent the difference between the number of heads and the number of tails obtained when a coin is tossed 6 times. When a coin is tossed 6 times , we have 64 outcomes which consists of : (i) 6 heads and 0 tails (ii) 5 heads and 1 tail (iii) 4 heads and 2 tails (iv) 3 heads and 3 tails (v) 2 heads and 4 tails (vi) 1 head and 5 tails (vii) 0 head and 6 tails . Let X represents the difference between the number of heads and tails. (i) ⇒ X = 6 – 0 = 6 (ii) ⇒ X = 5 – 1 = 4 (iii) ⇒ X = 4 – 2 = 2 (iv) ⇒ X = 3 – 3 = 0 (v) ⇒ X = 4 – 2 = 2 (vi) ⇒ X = 5 – 1 = 4 (vii) ⇒ X = 6 – 0 = 6 . Therefore , X = 6 , 4 , 2, 0 .

Here , probability of getting a spade from a deck of 52 cards = 13/52 = ¼ . p = ¼ , q = ¾ . 
let , x is the number of spades ,
then x has the binomial distribution with n = 5 , p = ¼ , q = ¾ .
P( none is a spade)= P (x = 0)