Question

A rock was dropped from a platform on a tower 55 feet above a lake. The rock landed on the bottom of the lake, which was 21 feet under the surface of the lake. Where was the rock when it had fallen halfway?

34 feet above the lake
38 feet above the lake
10.5 feet below the surface of the lake
17 feet above the lake

Answer 1

It was 55 feet to the water and then 21 feet from the water to the bottom.

The total distance the rock fell was 55 + 21 = 76 feet.

Halfway would be 76 / 2 = 38 feet.

55 - 38 = 17 feet above the lake.