Kathryn left the mall and drove towards the lake at an average speed of 52km/h.

Question

Kathryn left the mall and drove towards the lake at an average speed of 52km/h. Jenny left three hours later and drove in the opposite direction with an average speed of 60km/h. How long does Jenny need to drive before they are 380km/h apart?

***Note

Please provide a thorough explanation as to how you arrived to your conclusion.

Answer 1

3 hour head start + combined speeds * time = 380

52 * 3 + (52 + 60)*t = 380

156 + 112*t = 380

112 * t = 224

t = 2

TABLE:

Time Kathryn Jenny Total

0 0 0 0

1 52 0 52

2 52 0 52

3 52 0 52

4 52 60 112

5 52 60 112

totals 380