Question

Sarah left Minneapolis heading east on the interstate at a speed of 60mph. Her sister followed her on the same route, leaving 2 hours later and driving at a rate of 70mph. How long will it take for Sarah’s sister to catch up to Sarah?

Answer 1

14 hours from Sarah's perspective and 12 hours from Sarah's sister's perspective

Answer 2

12 hours

Explanation:

Let 't' be the time (in hours) for Sarah's sister to catch up to Sarah.

Sarah left Minneapolis ( t + 2 hours) and covered = 60 (t + 2) miles

Sarah's sister will cover the distance = 70 (t) miles

Now make an equation

70 (t) = 60 (t+2) (2 hours= 120 minutes)

70t = 60t + 120

70t - 60t = 120

10t = 120

t = 120/10 = 12 hours

It would take 12 hours for Sarah's sister to catch up to Sarah.