HARD
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A six-faced unbiased die is thrown until a number greater than 4 appears. The probability that this occurs on the n-th throw, where n is an even integer, is

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Important Questions on Probability

EASY
If A and B are any two events such that PA+PB-PA and B=PA, then
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
In a class, 40% of students study Maths and Science and 60% of students study Maths. What is the probability of a students studying Science given the student is already studying Maths?
HARD
Let A and B be two events such that PAB¯=16, PAB=14 and PA¯=14, where A¯ stands for the complement of the event A. Then the events A and B are 
EASY
An urn contains 5 red and 2 green balls. A ball is drawn at random from the urn. If the drawn ball is green, then a red ball is added to the urn and if the drawn ball is red, then a green ball is added to the urn; the original ball is not returned to the urn. Now, a second ball is drawn at random from it. The probability that the second ball is red, is:
HARD
Let E & F be two independent events. The probability that E & F happen is 112 and the probability that neither E nor F happens is 12 , then a value of PEPF is:
EASY
A coin is tossed and a die is rolled. The probability that the coin shows head and the die shows 3 is
HARD
If A and B are any two events such that PA=25 and PAB=320, then the conditional probability, PAAB, where A' denotes the complement of A, is equal to :
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 :

MEDIUM
If a fair coin is tossed 5 times, the probability that heads does not occur two or more times in a row is
HARD
Let A and E be any two events with positive probabilities 

Statement I: PE/APA/EPE.

Statement II: PA/EPAE.
HARD
Let X and Y be two events such that PX=13PXY=12 and PY|X=25. Then
HARD
One ticket is selected at random from 50 tickets numbered 00,01,02,....,49. Then, the probability that the sum of the digits on the selected ticket is 8, given that the product of these digits is zero, equals
EASY
If A and B are two events such that PA0 and PBA=1, then
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
Let A and B  be two non-null events such that AB. Then, which of the following statements is always correct?
MEDIUM
A problem in mathematics is given to three students A, B, C and their respective probability of solving the problem is 12,13 and 14, the probability that the problem will be solved is
EASY
For the events A and B, PA=34,PB=15,PAB=120 then PAB=
HARD
Two cards are drawn successively with replacement from a well-shuffled deck of 52 cards. Let X denote the random variable of number of aces obtained in the two drawn cards. Then PX=1+PX=2 equals:
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. A ball is drawn at random from box I and transferred to box II. If the probability of drawing a red ball from box I, after this transfer, is 13 , then the correct options(s) with the possible values of n1 & n2 is(are)