Chapter 7, Problem 18PTTS

To determine

To find: The more number of the girls than the number of the boys in the class.

Answer to Problem 18PTTS

The more number of the girls than the number of the boys in the class is $4$ .

Explanation of Solution

Given information: For every two boys in Tom’s science class, there are three girls. If there are $20$ students in the class, how many more girls than boys are in the class?

Calculation:

If for every two boys in Tom’s science class, there are three girls.

The total number of boys and girls are,

  $\begin{array}{l}=2+3\\ =5\end{array}$

Therefore, for every $5$ students there are $2$ boys and $3$ girls.

Let’s find the number of boys,

For every $5$ student there are $2$ boys

For every $1$ student there are $\frac{2}{5}$ boys

For every $20$ student there are,

  $\begin{array}{l}\frac{2}{5}\times 20\\ =2\times 4\\ =8\text{ boys}\end{array}$

Since, The total number of students in the class are $20$ .

Therefore, The number of girls in the class are $=$

  $20-$ The number of boys in the class

  $=20-8$

  $=12$

Hence, The more number of the girls than the number of the boys in the class is $=12-8$

  $=4$