Find Male Students: Calculating with 3/7 Female Ratio in 28-Student Class

Question

There are 28 students in a 9th grade class, $\frac{3}{7}$ of whom are female.

How many male students are there in the class?

00:00 How many boys are in the class?

00:05 The given number of girls

00:11 Subtract this ratio from the whole to find the number of boys

00:15 Convert from a whole number to an appropriate proper fraction

00:22 Find the common denominator

00:29 This is the relative quantity of boys

00:34 Multiply this ratio by the total number of students to find the number of boys

00:44 Move the multiplication to the numerator

00:51 Reduce the fraction, make sure to divide both numerator and denominator

01:09 Calculate the multiplication

01:15 And this is the solution to the question

Let's first split 28 into two fractions:

The first fraction will represent the girls:

$\frac{3}{7}$

The second fraction will represent the boys:

$1-\frac{3}{7}=\frac{7}{7}-\frac{3}{7}=\frac{4}{7}$

Now let's multiply the number of students by the fraction that represents the boys:

$28\times\frac{4}{7}$

Let's then multiply the numerator by 28:

$\frac{4\times28}{7}$

Now we can divide both the numerator and denominator by 7:

$\frac{4\times28:7}{7:7}=$

Finally, let's solve the division exercises in the numerator and denominator to get our answer:

$\frac{4\times4}{1}=4\times4=16$

$16$