Question

3/8 of the seventh grade students were taking advanced math at the beginning of the year, but seven dropped out by the end of the year. If there were 140 students taking advanced math at the end of the year, how many seventh grade students are there?

Answer 1

Answer:

392 students

Step-by-step explanation:

Given: 3/8 of the seventh grade students were taking advanced math at the beginning of the year.

          Seven dropped out by the end of the year.

          There are 140 students taking advanced math at the end of the year.

Lets assume total number of students of seventh grade be "x".

As given, 3/8 of the seventh grade students were taking advanced math at the beginning of the year.

∴ Number of student took advanced maths at the beginning= $\frac{3}{8} \times x= \frac{3x}{8}$

We know, 7 student dropped out of advanced math by the end of the year.

Now, forming an equation to determine number of students taking advanced math at the end of the year.

⇒ $\frac{3x}{8} -7= 140$

Solving the equation  to find number of student in seventh grade.

⇒ $\frac{3x}{8} -7= 140$

Adding both side by 7

⇒ $\frac{3x}{8} = 140+7$

Multiplying both side by 8

⇒$3x= 147\times 8$

Dividing both side by 3

⇒$x= \frac{147\times 8}{3}$

∴ $x= 392$

Hence, there are 392 students in seventh grade.