Question

A student is allowed to choose 4 questions out of 7. In how many ways can he choose them?​

Answer 1

he can answer the question in the probability of 4/7

Answer 2

∴ He can choose them in 35 ways.

Step-by-step explanation:

Given that, a student is allowed to choose 4 questions out of 7 questions.

To find the number of ways, we use combination formula.

$^nC_r= \frac{n!}{r!(n-r)!}$

n=Number of items in set.

r= Number of choosing an item from the set.

Here n= 7  and  r=4

Therefore the number ways of choose is

$=^7C_4$

$=\frac{7!}{4!(7-4)!}$

$=\frac{7!}{4!3!}$

$=\frac{7\times 6\times 5\times 4!}{4!3!}$

$=\frac{7\times 6\times 5}{1\times 2\times 3}$

=35

∴ He can choose them in 35 ways.