Tom drove away from Bigtown 10 minutes after Janice and overtook her in 20 minutes if tom drove at a speed of 90 mph what was janice's speed in mph?

Answer 1

Designate Janice's speed in miles per hour as j. The distance covered by each driver equals the speed multiplied by the total time driven. At the point of overtaking, the distances are equal. Therefore, from the problem statement:

90 mph X 20 minutes = 90 mph X 1/3 hour = 30 miles;

j(20 +10)/60 = 30 miles; 30 j = 60 X 60; or j = 60 X 30/30 = 60 mph.