NDA 2019 Paper 1 | Probability Question 89 | Mathematics

There are n socks in a drawer, of which 3 socks are red. If 2 of the socks are chosen randomly and the probability that both selected socks are red is $${1 \over 2}$$, then what is the value of n ?

NDA 2019 Paper 1

MCQ (Single Correct Answer)

+2.5

-0.83

Two cards are chosen at random from a deck of 52 playing cards. What is the probability that both of them have the same value ?

$${1 \over {17}}$$

$${3 \over {17}}$$

$${5 \over {17}}$$

$${7 \over {17}}$$

NDA 2019 Paper 1

MCQ (Single Correct Answer)

+2.5

-0.83

In eight throws of a die, 5 or 6 is considered a success. The mean and standard deviation of total number of successes is respectively given by

$${8 \over 3},{{16} \over 9}$$

$${8 \over 3},{4 \over 3}$$

$${4 \over 3},{4 \over 3}$$

$${4 \over 3},{{16} \over 9}$$

NDA 2019 Paper 1

MCQ (Single Correct Answer)

+2.5

-0.83

A and B are two events such that $$\overline A $$ and $$\overline B $$ are mutually exclusive. If P(A) = 0.5 and P(B) = 0.6, then what is the value of P(A / B) ?

$${1 \over 5}$$

$${1 \over 6}$$

$${2 \over 5}$$

$${1 \over 3}$$

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