A letter carrier can deliver mail to 112 homes per hour by walking and 168 homes per hour by driving. By what percent is productivity increased by driving?

To calculate the percentage increase in productivity, we need to compare the difference between the number of homes delivered by driving and walking relative to the number of homes delivered by walking.

First, let's find the difference in the number of homes delivered by driving and walking:
Number of homes delivered by driving: 168
Number of homes delivered by walking: 112

Difference = 168 - 112 = 56

Now, let's calculate the percentage increase in productivity:
Percentage Increase = (Difference / Number of homes delivered by walking) * 100

Percentage Increase = (56 / 112) * 100

Percentage Increase = 0.5 * 100

Percentage Increase = 50%

Therefore, the productivity is increased by 50% when delivering mail by driving compared to walking.