Let N denote the sum of the numbers obtained when two dice are rolled. If the probability that 2 N < N !…

Let N denote the sum of the numbers obtained when two dice are rolled. If the probability that 2N<N! is mn where m and n are coprime, then 4m-3n is equal to 
  1. 6
  2. 12
  3. 10
  4. 8

Solution

Given that,

2N<N!

N is the sum of numbers of two dice.

2N12

Let us check the given condition 2N<N!

N=1 (not possible) 0

N=2 (not possible) 1

N=3 (not possible) 2

N=4 (possible)

We need to find the probability for N4.

PN4=1-PN=2-PN=3

=1-136-236

=1112=mn

Now let us find 4m-3n.

=4×11-3×12=8.

Hence, the required answer is 8.

Asked in: JEE Main 2023 (10 Apr Shift 1)

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