Exercise 31A

In a lottery, a person chooses six different numbers at random from 1 to 20. If these six numbers match with the six numbers already fixed by the lottery committee, he wins the prize. What is the probability of winning the prize in the game?

Answer : All numbers are different (given in question), this will be the same as picking r different objects from n objects which is ncr Here, n= 20 and r = 6(as we have to pick 6 different objects...

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A combination lock on a suitcase has 3 wheels, each labeled with nine digits from 1 to 9. If an opening combination is a particular sequence of three digits with no repeats, what is the probability of a person guessing the right combination?

Answer : As repetition is not allowed total no.of cases possible is 9×8×7(because if one of the numbers occupies a wheel, then the other wheel cannot be occupied by this number, i.e. next wheel have...

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