Kate rode her bicycle for 30 minutes at a speed of 16 \mathrm{mph}, then walked for 90 minutes at a speed of 4 \mathrm{mph}. What was her overall average speed in miles per hour?
Answer Choices
A. 7
B. 9
C. 10
D. 12
E. 14
Kate rode her bicycle for 30 minutes at a speed of 16 \mathrm{mph}, then walked for 90 minutes at a speed of 4 \mathrm{mph}. What was her overall average speed in miles per hour?
Answer Choices
A. 7
B. 9
C. 10
D. 12
E. 14