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?

00:07 Let's figure out how many boys are in the class.

00:12 We know the number of girls already.

00:18 Now, subtract this part from the total to find the boys.

00:23 Next, convert it to a proper fraction.

00:29 Find a common denominator.

00:36 This gives us the fraction of boys.

00:41 Multiply this fraction by the total class size.

00:51 Make sure to move the multiplication to the numerator.

00:58 Now, simplify the fraction by dividing the top and bottom.

01:16 Do the multiplication.

01:22 And that's how we solve the problem!

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:

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

$16$