Question

There is an alien machine which produces seven aliens every two seconds. At this rate how many aliens will produces in one hour?

Answer 1

well, there are 60 minutes in 1 hour, and there are 60 seconds in 1 minute, so in 60 minutes, there are 60 * 60 seconds, or 3600 seconds in 60 minutes, or 1 hour, therefore, in 1 hour there are 3600 seconds.

the machine makes 7 aliens in 2 seconds, how many will it make in 3600 seconds?

$\bf \begin{array}{ccll} aliens&seconds\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 7&2\\ a&3600 \end{array}\implies \cfrac{7}{a}=\cfrac{2}{3600}\implies \cfrac{7\cdot 3600}{2}=a$

that many.

Answer 2

There are 3600 seconds in one hour.

Set up a proportion.

Let A = number of aliens in one hour

7/A = 2/3600

2A = 7(3600)

2A = 25,200

A = 25,200 ÷ 2

A = 12,600

So, 12,600 aliens are produced in one hour.