Question

There is a school were 60% are girls and of which 45% are poor. Students are selected at random, what is the probability of selecting a poor girl out of total strength.

Answer 1

The formula for calculating probability is as follows: 

Probability  = event / number of possible outcomes

We can calculate our event ( picking a poor girl) in the following manner: 

Total number of girls = 60%

Poor girls are 45% of the total number of girls = 45/100 x 60 /100 = 27/100( = 0.27)

The total strength ( which is also the possible outcomes is 100%)

There probability of picking a poor girl = 0.27 ÷ 1 ×100%

                                                              = 27%

Answer 2

Solution :-

Let the total number of students be 100.

There are 60 % girls. 

So, the number of girls = (100*60)/100 

= 60 girls

Out of the total girls, 45 % are poor.

So, number of poor girls = (45*60)/100

= 27 girls are poor.

Hence, the probability of selecting a poor girl out of the total strength

= 27/100

  27/100 = 0.27