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If any four numbers are selected and they are multiplied, then the probability that the last digit will 1,3,5 or 7, is

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Important Questions on Probability

HARD
If the lengths of the sides of a triangle are decided by the three throws of a single fair die, then the probability that the triangle is of maximum area given that it is an isosceles triangle, is:
HARD

If 12 identical balls are to be placed in 3 identical boxes, then the probability that one of the boxes contains exactly 3 balls is

HARD
Let X be a set containing 10 elements and PX be its power set. If A and B are picked up at random from PX, with replacement, then the probability that A and B have equal number of elements is:
HARD
If two different numbers are taken from the set 0, 1, 2, 3,....., 10; then the probability that their sum as well as absolute difference are both multiple of 4, is:
MEDIUM

Six persons A, B, C, X, Y & Z go for an interview. What is the probability of selection of A and Y in the interview?

HARD
Two different families A and B are blessed with equal number of children. There are 3 tickets to be distributed amongst the children of these families so that no child gets more than one ticket. If the probability that all the tickets go to the children of the family B is 112, then the number of children in each family is
HARD
A multiple choice examination has 5 questions. Each question has three alternative answers out of which exactly one is correct. The probability that a student will get 4 or more correct answers just by guessing is :
MEDIUM
A letter is taken at random from the word "STATISTICS" and another letter is taken at random from the word "ASSISTANT". The probability that they are same letters is
EASY

In a college, 15th of the girls and 18th of the boys took part in a social camp. The total number of students in the college took part in the camp is:

HARD
Four dice are thrown simultaneously and the numbers shown on these dice are recorded in 2×2 matrices. The probability that such formed matrices have all different entries and are non-singular, is:
MEDIUM
A quadratic equation ax2+bx+c=0   with distinct coefficients is formed. It a,b,c are chosen from the numbers 2,3 and 5, then the probability that the equation has real roots is
MEDIUM
A determinant of second order is made with the elements 0, 1. What is the probability that the determinant is positive?
EASY
An ellipse of eccentricity 223 is inscribed in a circle. A point is chosen inside the circle at random. The probability that the point lies outside the ellipse is
EASY
The probability that among 7 persons, no 2 were born on the same day of a week is
MEDIUM
Let a and b be 2 consecutive integers selected from the first 20 natural numbers. The probability that a2+b2+a2b2 is an odd positive integer is
HARD
From a group of 10 men and 5 women, four member committees are to be formed each of which must contain at least one women. Then the probability for these committees to have more women than men, is :
HARD
If a 3-digit number is randomly chosen. What is the probability that either the number itself or some permutation of the number (which is a 3-digit number) is divisible by 4 and 5?
MEDIUM
Two persons A and B throw a die alternatively till one of them gets a three and wins the game. Find their respective probabilities of winning.
MEDIUM
A person throws two fair dice. He wins Rs. 15 for throwing a doublet (same numbers on the two dice), wins Rs 12 when the throw results in the sum of 9 , and loses Rs. 6 for any other outcome on the throw. Then the expected gain/loss (in Rs.) of the person is:
EASY
Let A and B are two mutually exclusive events with P( A )= 1 3 and P( B )= 1 4 . What is the value P( A ¯ B ¯ )?