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  • n is selected from the set {1,2,3......49} and the number 2n+3n+5n is formed. Total number of ways of selecting n so that the formed number is divisible by 4 is equ

n is selected from the set {1,2,3......49} and the number 2n+3n+5n is formed. Total number of ways of selecting n so that the formed number is divisible by 4 is equal to

Option: 1

24


Option: 2

26


Option: 3

27


Option: 4

21


Answers (1)

best_answer

If n is odd

3n=4a+1, 5n -1 is divisible by 4 only when n is greater than or equal 2.

Now 4a+1+5n -1+2n is divisible by 4

Thus, n=3,5,7............49.

If n is even and greater than 2

3n=4a-1, 5n-1 is not divisible by 4.

The total number of ways of selecting n is 24.

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Sayak

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