Question

In how many ways can 2 singers be selected from 4 who came to an audition?

Answer 1

First part  its 4C2  = 4*3 / 2 = 6

Second part
12 * 100
----------    =   4.3 %
   280

Answer 2

Answer: A. 6

A. 4.3%

Step-by-step explanation:

The total number of singers = 4

To choose singers = 2

The number of ways to choose 2 singers from 4= $^4C_2=\frac{4!}{2!(4-2)!}=3\times2=6$

Hence, A is the right option.

The total number of water purifiers  T= 280

The number of defective purifiers D= 12

The probability that a water purifier chosen at random will be defective (in percent)=$\frac{\text{T}}{\text{D}}\times100$

$=\frac{12}{280}\times100\\=0.042857\times100\\=4.2857\%\approx4.3\%$

Hence, A is the right option.