Question

A person tosses a coin 25 times. In how many ways can he get 10 tails?

Answer 1

STEP - BY - STEP EXPLANATION

What to find?

The number of ways to get 10 tails.

Given:

Number of time the coin is tosses(n) =25

and r=10 ; 10 tails (getting tails success and heads failure).

Since, the number of tosses is 25 and we want to get 10 tails, then we can solve this using combination.

Step 1

Recall the combination formula.

`nC_r=(n!)/((n-r)!r!)`

n= 25 r=10

Step 2

Substitute the values into the formula and simplify.

`25C_(10)=(25!)/((25-10)!10!)`
`=(25!)/(15!*10!)`
`=(25*24*23*22*21*20*19*18*17*16*15!)/(15!*10!)`
`=(25*24*23*22*21*19*18*17*16)/(10*9*8*7*6*5*4*3*2)`
`=3268760`

ANSWER

3268760 ways.