Answer:
He will need to cut off 2.57 inches off of the new pipe.
Explanation:
We can calculate how many inches the plumber needs to cut off the 10 inch pipe by finding the difference between the 10 inch pipe and the 7.43 inch pipe.
So let’s subtract 7.43 from 10.
10-7.43 = 2.57
The difference is 2.57 inches, and therefore the plumber will need to cut 2.57 inches off of the new pipe to make it fit where the 7.43 inch pipe used to be.