MEDIUM
JEE Main
IMPORTANT
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When a missile is fired from a ship, the probability that it is intercepted is 13 and the probability that the missile hits the target, given that it is not intercepted, is 34. If three missiles are fired independently from the ship, then the probability that all three hit the target, is:

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Important Questions on Probability

HARD
JEE Main
IMPORTANT
Let A be a set of all 4 -digit natural numbers whose exactly one digit is 7. Then the probability that a randomly chosen element of A leaves remainder 2 when divided by 5 is:
HARD
JEE Main
IMPORTANT
In a group of 400 people, 160 are smokers and non-vegetarian; 100 are smokers and vegetarian and the remaining 140 are non-smokers and vegetarian. Their chances of getting a particular chest disorder are 35%,20% and 10% respectively. A person is chosen from the group at random and is found to be suffering from the chest disorder. The probability that the selected person is a smoker and non-vegetarian is :
MEDIUM
JEE Main
IMPORTANT
A fair coin is tossed a fixed number of times. If the probability of getting 7 heads is equal to probability of getting 9 heads, then the probability of getting 2 heads is
MEDIUM
JEE Main
IMPORTANT
A seven digit number is formed using digits 3,3,4,4,4,5,5. The probability, that number so formed is divisible by 2, is
HARD
JEE Main
IMPORTANT
Box 1 contains 30 cards numbered 1 to 30 and Box 2 contains 20 cards numbered 31 to 50. A box is selected at random and a card is drawn from it. The number on the card is found to be a non-prime number. The probability that the card was drawn from Box 1 is 
HARD
JEE Main
IMPORTANT
Let EC denote the complement of an event E. Let E1,E2 and  E3 be any pairwise independent events with PE1>0 and PE1E2E3=0, then PE2CE3C/E1 is equal to
MEDIUM
JEE Main
IMPORTANT
A die is thrown two times and the sum of the scores appearing on the die is observed to be a multiple of 4. Then the conditional probability that the score 4 has appeared at least once is
MEDIUM
JEE Main
IMPORTANT
Let xi1i10 be ten observation of a random variable X. If i=110xi-p=3 and i=110xi-p2=9 where 0pR, then the standard deviation of these observations is: