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JEE Advanced2023MathematicsPermutation and CombinationActual

Let X be the set of all five digit numbers formed using 1 , 2 , 2 , 2 , 4 , 4 , 0 . For example, 22240 is in X while 02244 and 44422 are not in X . Suppose that each element of X has an equal chance of being chosen. Let p be the conditional probability that an element chosen at random is a multiple of 20 given that it is a multiple of 5 . Then the value of 38 p is equal to

Correct answer

0

Step-by-step solution

First we will find the sample space in which the number of five-digit numbers are divisible by 5 , So, fixing zero at the last place we get, - - - - 0 ⏟ Now in first four place following number can take place, 2224   → 4 ! 3 ! = 4   ways 2244 → 4 ! 2 ! 2 ! = 6   ways 2221 → 4 ! 3 ! = 4   ways 2241 → 4 ! 2 ! = 12   ways 2441 → 4 ! 2 ! = 12   ways So, total sample space will be 4 + 6 + 4 + 12 + 12 = 38 Now finding the number of favourable outcomes, So,

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