# A school library needs four computer for every 7 students. If the school has 280 students, how many computers does it need?

Oct 26, 2016

The school needs $160$ computers.

#### Explanation:

School needs $4$ computers for $7$ students.
$\implies 7$ students need $4$ computers.

$\implies 1$ student need $\frac{4}{7}$ computers.

$\implies 280$ students need $\frac{280 \cdot 4}{7}$ computers.

$\implies 280$ students need $\left(40 \cdot 4\right)$ computers.

$\implies 280$ students need $160$ computers.

$\implies$ The school needs $160$ computers.

Mar 2, 2017

$160$ computers

#### Explanation:

We can read from this that for every group of $7$ students there should be 4 computer.

It will help to find out how many groups of $7$ students there are in the school.

$280 \div 7 = 40$ groups

Each group should have 4 computers:

$40 \times 4 = 160$ computers

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We can also do this by direct proportion where we compare the number of students with the number of computers.

("students"rarr)/("computers"rarr) " "7/4 = 280/x

$7 x = 280 \times 4$

$x = \frac{280 \times 4}{7}$

$x = 160$