A survey was sent to 60 customers, 7 of whom responded

A survey was sent to 60 customers, 7 of whom responded. Then the survey was redesigned and sent to another 72 customers, 9 of whom responded. By approximately what percent did the response rate increase from the original survey to the redesigned survey?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #40376