Question

A group of 80 students went on a picnic. 15% of them were girls. How many girls were there in the group? How many were boys?

Answer 1

Hint: We start solving the by assigning the variable for the total number of girls in the group and finding the total number of boys in that group. We then find the total number of girls in the group using the fact that a% of b is ${\displaystyle \frac{a}{100}}\times b$. We then find the total number of boys by subtracting the total number of girls from 80 students.

Complete step by step answer:
According to the problem, we are given that a group consisting of 80 students went to a picnic and 15% of them were girls. We need to find the total number of girls and boys present in that group.
Let us assume the total number of girls is ‘x’. Then the total number of boys will be $(80-x)$.
We are given that 15% of the total 80 students are girls. So, we get x = 15% of 80.
We know that a% of b is defined as ${\displaystyle \frac{a}{100}}\times b$.
So, we get $x={\displaystyle \frac{15}{100}}\times 80$.
$\Rightarrow x={\displaystyle \frac{1200}{100}}$.
$\Rightarrow x=12$.
So, we have found that there are 12 girls in the group.
Now, let us find the total number of boys in the group. So, we get the total number of boys as $80-x=80-12=68$.

∴ The group contains 12 girls and 68 boys.

Note: We should confuse that there are 15 girls in the group instead of 15% of the students which is the most common mistake. We can also find the total number of boys by first finding the percentage of the boys present in the group and following the similar procedure we did for finding the total number of girls. We should not confuse a% of b with $a\times b$ instead of ${\displaystyle \frac{a}{100}}\times b$. Similarly, we can expect problems to find the total percentage of the girls if 10 more girls are added to this group.