College ? of the Day

Read the following SAT test question, then select your answer.

A geologist has 10 rocks of equal weight. If 6 rocks and a 10-ounce weight balance on a scale with 4 rocks and a 22-ounce weight, what is the weight, in ounces, of one of these rocks?

1. 4
   
2. 5
   
3. 6
   
4. 7
   
5. 8