A science museum has a display called a sewer pipe symphony. It consists of many plastic pipes

Question:

A science museum has a display called a sewer pipe symphony. It consists of many plastic pipes of various lengths, which are open on both ends.
(a) If the pipes have lengths of 3.0m, 2.5m, 2.0m, 1.5m and 1.0m, what frequencies will be heard by a visitor’s ear places near the ends of the pipes?
(b) What does this display work better on a noisy day than on a quiet day?