176k views
5 votes
an experienced bricklayer can construct a small wall in 7 hours. An apprentice can complete the job in 42 hours

1 Answer

7 votes

Answer:

6 hours

Explanation:

The trick to this type of problem is using an equal amount of time.

The least common multiple of 7 and 42 is 42

At 7 hours per wall

In 42 hours the bricklayer could build

42/7 = 6 walls

At 42 hours per wall

In 42 hours the apprentice could build

42/1 = 1 walls

Working together in 42 hours they could build 6 + 1 = 7 walls

42hours/7walls = 6hours/ wall

--------------------------

Math only

x = 1 wall/7hours + 1wall/42 hours

use common denominator of 42

x = 6w/42 hr + 1w/42hr

x = 7w/42 hr

reduce

x = 1w / 6hr

User IftekharDani
by
7.1k points