Question

An industrial machikne is able to make 9 pens in 3 seconds. What is the rate made per second?

Answer 1

This problem can be solved using proprtions.  Once you set up the proportion, the calculations are easy.

Let x = number of pens made in 1 second.

$\frac{9pen}{3sec} = \frac{xpen}{1 second}$

Now, you just cross multiply and solve.

9 = 3x

x = 3

The rate is 3 pens per second.