Explanation

Jenny must complete 3000 gear shafts in 10 hours, which is a rate of 300 gear shafts per hour.

Percent change is \(\frac{difference}{original} \times 100\). In this case, the difference is 50 and the original
is 250, so the percent change is \(\frac{50}{250} \times 100\).

The question asks for percent increase, so be sure to enter 20, and not 0.2.

Hence answer is 20.