HSC Science (Computer Science) 12th Board Exam - Maharashtra State Board Question Bank Solutions for Mathematics and Statistics

A random variable X has the following probability distribution:

then E(X)=....................

From a lot of 25 bulbs of which 5 are defective a sample of 5 bulbs was drawn at random with replacement. Find the probability that the sample will contain -

(a) exactly 1 defective bulb.

(b) at least 1 defective bulb.

From a lot of 15 bulbs which include 5 defectives, a sample of 4 bulbs is drawn one by one with replacement. Find the probability distribution of number of defective bulbs. Hence find the mean of the distribution.

Probability distribution of X is given by

Find P(X ≥ 2) and obtain cumulative distribution function of X

Find the probability distribution of number of heads in two tosses of a coin.

Find the probability distribution of number of tails in the simultaneous tosses of three coins.

Find the probability distribution of number of heads in four tosses of a coin

Find the probability distribution of the number of successes in two tosses of a die, where a success is defined as

(i) number greater than 4

(ii) six appears on at least one die

From a lot of 30 bulbs which include 6 defectives, a sample of 4 bulbs is drawn at random with replacement. Find the probability distribution of the number of defective bulbs.

A coin is biased so that the head is 3 times as likely to occur as tail. If the coin is tossed twice, find the probability distribution of number of tails.

Two dice are thrown simultaneously. If X denotes the number of sixes, find the expectation of X.

Two numbers are selected at random (without replacement) from the first six positive integers. Let X denotes the larger of the two numbers obtained. Find E(X).

If the probability that a fluorescent light has a useful life of at least 800 hours is 0.9, find the probabilities that among 20 such lights at least 2 will not have a useful life of at least 800 hours. [Given : (0⋅9)¹⁹ = 0⋅1348]

A random variable X ~ N (0, 1). Find P(X > 0) and P(X < 0).

Let X represent the difference between the number of heads and the number of tails when a coin is tossed 6 times. What are the possible values of X?

For  the following probability density function (p. d. f) of X, find : (1) P ( X<1) , (2) P |x| < 1

if f(x) =`"x"^2/18 , -3<"x" <3`

= 0 , otherwise

For  the following probability density function (p. d. f) of X, find : (i) P ( X<1), (ii) P |x| < 1 

if `f(x) ="x"^2/18 , -3 < x < 3`

           = 0,             otherwise

If X ∼ N (4,25), then find P(x ≤ 4)

The p.m.f. of a random variable X is
`"P"(x) = 1/5` , for x = I, 2, 3, 4, 5 
        = 0 , otherwise.
Find E(X).

The defects on a plywood sheet occur at random with an average of the defect per 50 sq. ft. What Is the probability that such sheet will have-

(a) No defects
(b) At least one defect 
[Use e^-1 = 0.3678]