Question

Lucy and her friends decided they wanted to take a road trip to the beach. During their first part of the trip they traveled 82 miles in 1 hour and 10 minutes which is (70.2857 mi/hr) averaged but the traffic was slow because of weather. During the second part of the trip to the beach Lucy and her friend's have 152 miles left but now there is no bad weather so Lucy can go faster. 1.) Find how long the second part of the trip will take if Lucy wants her average speed for the entire trip to be 85mi/hr. 2.) Find what would be the average speed for the second part of Lucy’s trip.

Answer 1

Part 1.

Given that average speed of entire trip is 85 mi/hr, So

V_avg = total distance traveled/total time taken

So, total distance traveled = 82 miles + 152 miles = 234 miles

V_avg = 85 mi/hr

So,

total time taken = total distance traveled/V_avg

total time taken = 234 mi/(85 mi/hr) = 2.753 hrs = 2 hrs and 45 minutes

T = t1 + t2

Given that time taken in 1st part = 1 hr 10 min, So

t2 = T - t1

t2 = 2 hr 45 min - 1 hr 10 min

t2 = 1 hr 35 min = 1.583 hrs

Part B.

Average speed of 2nd part = distance traveled in second part/time taken in 2nd part

V2_avg = 152 miles/1.583 hrs

V2_avg = 96.0202 mi/hr = 96.0 mi/hr

Let me know if you've any query.