A restaurant occupying the top floor of a skyscraper rotates

A restaurant occupying the top floor of a skyscraper rotates as diners enjoy the view. Ling and Sarah notice that they began their meal at 7:00 p.m. looking due north. At 7:45 p.m. they had rotated 180° to a view that was due south. At this rate, how many degrees will the restaurant rotate in 1 hour?

1. 90°
2. 180°
3. 240°
4. 270°
5. 400°

Answer

The correct answer is C.

The restaurant is rotating 180° in 45 minutes. That means it is rotating 60° every 15 minutes.

That is 240° every 60 minutes or 1 hour.

Algebraically, you can set up a proportion:

180°/45 = x/60

x = 180° x 60/45

x = 240°.