Question

A machine can fill a box with twenty pencils in 30 seconds. How many boxes can the machine fill in 2 hours?

Answer 1

4800 pencils or 240 boxes 

Answer 2

Answer:

use conversion:

1 hour = 3600 seconds.

As per the given statement:

A machine can fill a box with twenty pencils in 30 seconds.

Number of pencils = 20

Time = 30 seconds = $\frac{1}{120}$ hours.

then by definition of unit rate;

$\text{Unit rate per hour} = \frac{20}{\frac{1}{120}}= 20 \cdot 120 = 2400$

we have to find the number of boxes can the machine fill in 2 hours.

$\text{Number of pencils} = \text{Unit rate per hour} \times 2$

Substitute the given values we have;

$\text{Number of pencils} = 2400 \times 2 = 4800$

it is given that:

20 pencils fill = 1 box

4800 pencils fill = 240 boxes

Therefore, 240 boxes can the machine fill with 4800 pencils  in 2 hours