MEDIUM
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Let a die be rolled n times. Let the probability of getting odd numbers seven times be equal to the probability of getting odd numbers nine times. If the probability of getting even numbers twice is k215, then k is equal to

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Important Questions on Binomial Distribution

HARD
Four persons independently solve a certain problem correctly with probabilities 12,34,14,18. Then the probability that the problem is solved correctly by at least one of them is
HARD
Let A, B and C be three events, which are pair-wise independent and E¯ denotes the complement of an event E. If PABC=0 and PC>0, then PA¯B¯|C is equal to
MEDIUM

For the following distribution function F(x) of a random variable X

x 1 2 3 4 5 6
F(x) 0.2 0.37 0.48 0.62 0.85 1

P 3<X 5=

HARD
Let A and E be any two events with positive probabilities 

Statement I: PE/APA/EPE.

Statement II: PA/EPAE.
HARD
If the mean and the variance of a binomial variate X  are 2 & 1 respectively, then the probability that X takes a value greater than or equal to one is:
HARD
If Aand B are two events such that PAB=PAB, then the incorrect statement amongst the following statements is :
MEDIUM
A box contains b blue balls and  r red balls. A ball is drawn randomly from the box and is returned to the box with another ball of the same colour. The probability that the second ball drawn from the box is blue, is
HARD
Let two fair six-faced dice A and B be thrown simultaneously. If E1 is the event that die A shows up four, E2 is the event that die B shows up two and E3 is the event that the sum of numbers on both dice is odd, then which of the following statements is not true?
MEDIUM
If a fair coin is tossed 5 times, the probability that heads does not occur two or more times in a row is
MEDIUM
A shooter can hit a given target with probability 14. She keeps firing a bullet at the target until she hits it successfully three times, and then she stops firing. The probability that she fires exactly six bullets lies in the interval
MEDIUM
A bag contains 4 red and 6 black balls. A ball is drawn at random from the bag, its color is observed and this ball along with two additional balls of the same color are returned to the bag. If now a ball is drawn at random from the bag, then the probability that this drawn ball is red, is:
HARD
An unbiased coin is tossed. If the outcome is a head then a pair of unbiased dice is rolled and the sum of the numbers obtained on them is noted. If the toss of the coin results in tail then a card from a well-shuffled pack of nine cards numbered 1, 2, 3,, 9 is randomly picked and the number on the card is noted. The probability that the noted number is either 7 or 8 is
HARD
An experiment succeeds twice as often as it fails. The probability of at least 5  successes in the six trials of this experiment is
HARD
Two persons A and B throw a (fair) die (six-faced cube with faces numbered from 1 to 6) alternately, starting with A. The first person to get an outcome different from the previous one by the opponent wins.The probability that B wins is,
HARD
Let n1 & n2 be the number of red and black balls, respectively, in box I. Let n3 & n4 be the number of red and black balls, respectively, in box II. One of the two boxes, box I and box II, was selected at random and a ball was drawn randomly out of this box. The ball was found to be red. If the probability that this red ball was drawn from box II is 13, then the correct option(s) with the possible values of n1, n2, n3 & n4 is(are)
HARD
The minimum number of times one has to toss a fair coin so that the probability of observing at least one head is at least 90% is:
HARD
There are three bags B1,B2 and B3. The bag B1 contains 5 red and 5 green balls, B2 contains 3 red and 5 green balls, and B3 contains 5 red and 3 green balls, Bags B1,B2 and B3 have probabilities 310,310 and 410 respectively of being chosen. A bag is selected at random and a ball is chosen at random from the bag. Then which of the following options is/are correct?
EASY
If A and B are events with PAB=34,P A=23 and PAB=14 then PB is
HARD

In a random experiment, a fair die is rolled until two fours are obtained in succession. The probability that the experiment will end in the fifth throw of the die is equal to :

HARD

A computer producing factory has only two plants T1 and T2. Plant T1 produces 20% and plant T2 produces 80% of the total computers produced. 7% of computers produced in the factory turn out to be defective. The probability that a computer turns out to be defective which is produced in plant T1 is ten times of the computers produced in the plant T2. A computer produced in the factory is randomly selected and it does not turn out to be defective. Then the probability that it is produced in plant T2 is