Question

Of the 50 students in the cafeteria, 7 have red hair. Suppose there are 750 students in the school. Write a proportion that could be used to predict the number of students who have red hair. Use x to represent the number of students who have red hair.

Answer 1

Given:

Of the 50 students in the cafeteria, 7 have red hair.

Total number of students = 750

To find:

The proportion that could be used to predict the number of students who have red hair.

Solution:

Let x represent the number of students who have red hair.

The ratio of student having red hair to the total number of students are

$Ratio_1=\dfrac{7}{50}$

$Ratio_2=\dfrac{x}{750}$

The number of students having red hair is proportional to the total number of students. So, the above ratios are equal.

$\dfrac{x}{750}=\dfrac{7}{50}$

Multiply both sides by 750.

$\dfrac{x}{750}\times 750=\dfrac{7}{50}\times 750$

$x=7\times 15$

$x=105$

Therefore, the required equation is $\dfrac{x}{750}=\dfrac{7}{50}$ and the number of students who have red hair is 105.