Question

Sally can paint a room in 5 hours while it takes Steve 3 hours. How long would it take them to paint if they worked together

Answer 1

It would be 8 hours because you are adding 5 and 3 to get a total

Answer 2

Answer: it will take them 1.875 hours to paint if they worked together

Step-by-step explanation:

Sally can paint a room in 5 hours. This means that in 1 hour, 1/5 of the room. Her unit rate is 1/5

Steve 3 hours to paint the same room. It means that his unit rate per hour is 1/3

If they work together, it would take a lesser time because they would be working simultaneously and at their individual rates. It means that their rates are additive. Their combined individual rate will be 1/5 + 1/3

Assuming they worked together and finished the painting in t hours, their combined rate per hour will be 1/t. Therefore

1/5 + 1/3 = 1/t

3 + 5/15 = 1/t

8/15 = 1/t

8t =15

t = 15/8 = 1.875 hours