Jerry travels 8 miles at an average speed of 40 miles per hour, stops

Question

Jerry travels 8 miles at an average speed of 40 miles per hour, stops for 10 minutes, and then travels another 20 miles at an average speed of 60 miles per hour. What is Jerry’s average speed, in miles per hour, for this trip?

A. 40
B. 42.5
C. 44
D. 50
E. 52.5

Kudos for a correct solution.

A. 40
B. 42.5
C. 44
D. 50
E. 52.5

CounterSniper · Answer

Time Taken for the first part of the journey= 8/40 = 1/5 hr=12 min

Idle time =10 min

Time Taken for the second part of the journey= 20/60= 1/3 hr =20 min

Total time taken =42 min = 7/10 hr

Total distance = 28 miles

therefore avg speed (28/7)*10 =40 miles per hour

--> : A

GMATinsight · Answer

Total Time taken by jerry = (8/40)*60 Minutes + 10 Minutes + (20/60)*60 Minutes = 42 Minutes

Average Speed = Total Distance / Total Time = (8+20) miles / (42/60)Hours = 28*60 / 42 = 40 Miles per hour

Answer: option A

VenoMfTw · Answer

IMO: A

Avg speed =  \frac{Total distance}{Total time}

Total distance = 20+8 = 28 miles
Total time = t1+t2+t3
t1= 8 miles at an average speed of 40 miles per hour ==> 8/40 = 1/5 hr
t2 = 10 minutes idle time = 10/60 = 1/6 hr
t3 = 20 miles at an average speed of 60 miles per hour ==> 20/60 = 1/3 hr
Total time = 1/5 + 1/6 + 1/3 = 7/10

Avg speed =  \frac{28*10}{7}  = 40 miles per hr

jasimuddin · Answer

total distance = 8+20 =28 miles
time = distance/ speed
total time = 8/40 (to go 1st 8 miles) + 10/60 (break) + 20/ 60 (to go 2nd 60 miles)
 = 7/10 hours
average speed = total distance / total time
 = 28 /(7/10)
 =40 miles per hour
ans: A

TimeTraveller · Answer

Total distance traveled =  8+20 = 28 .
Total time taken =  \frac{60*8}{40} + 10 + 20 = 12 + 10 + 20 = 42  mins.

Average speed =  \frac{28*60}{42} = 40  mph. Ans (A).

Heman105 · Answer

Average Speed = Total Distance / Total Time

Total distance = 8+20 = 28 miles

Total time = ((8/40)*60) + 10 + ((20/60)*60) = 42 mins = 42/60 hrs

Average speed = (28/42)*60 = 40 miles per hr

Bunuel · Answer

800score Official Solution:

Since Rate = Distance/Time, the average rate at which Jerry travels over a certain distance can be found by dividing the total distance of the trip by the total time for the trip.

Let’s find the times for the various portions of the trip using the formula Time = Distance / Rate:
Traveling 8 miles at a speed of 40 miles per hour takes 8/40 = 1/5 hour.
Similarly, traveling 20 miles at 60 miles per hour takes 20/60 = 1/3 hour.
The 10 minutes he was stopped is equal to 1/6 of an hour.

Adding all these times together gives us the total time:
Total time = 1/5 + 1/3 + 1/6
= 6/30 +10/30 + 5/30 = 21/30
= 7/10 hour.

The total distance traveled is 28 miles.

Therefore, the average speed is:
= 28 / (7/10) = 28 × (10/7) = 40 miles per hour.

The correct answer is choice (A).

ScottTargetTestPrep · Answer

Using the formula Average = total distance/total time, we have:

Average = 28/(8/40 + 1/6 + 20/60)

Average = 28/(1/5 + 1/6 + 1/3)

Average = 28/(6/30 + 5/30 + 10/30)

Average = 28/(21/30) = (30 x 28)/21 = (30 x 28)/(3 x 7) = 10 x 4 = 40.

Answer: A

jalice · Answer

Total time travelled by Jerry= 60*8/40+10+60*20/60= 12+10+20= 42 mins
Total distance travelled by Jerry= 8+20= 28 miles
Average speed= total distance/total time= 28/42= 2/3 miles per min= 2*60/3= 40 miles per hour.

Ans (A)

johnhohng · Answer

Formula: D = RT

Given:

D_1 = 8 miles 
 R_1 = 40 mph 
 T_1 = \frac{{D_1}}{{R_1}} = \frac{{8 miles}}{{40 mph}} = \frac{1}{5}hour 
Convert minutes to hours because the final answer needs to be in miles per  hour 
 T_2 = 10 minutes = \frac{1}{6}hour 
 D_3 = 20 miles 
 R_3 = 60 mph 
 T_3 = \frac{{D_3}}{{R_3}} = \frac{{20 miles}}{{60 mph}} = \frac{1}{3}hour 
Total distance = 8 miles + 20 miles = 28 miles

Solve:

1. Solve for overall rate using D = RT

2. In order to get total time, find the sum of all provided times:  T_1 + T_2 + T_3 = \frac{1}{5}hour + \frac{1}{6}hour + \frac{1}{3}hour = (7/10)hour

3.  \frac{D}{T} = \frac{{28 miles}}{(7/10)hour}  = 40 mph

Salsanousi · Answer

T1 = 8/40 = 1/5

Time stopped = 10 mins = 1/6

T2 = 20/60 = 1/3

Total time = 1/5 + 1/3 + 1/6 = 6 + 10 + 5 = 21/30 = 7/10

Avg speed = total distance/total time

= 20 + 8 = 28/(7/10) = (28*10)/7 = 4*10 = 40

Answer choice A

Posted from my mobile device

KanishkM · Answer

Average Speed = Total Distance / Total Time

Total Distance = 28

Total Time = 8/40 + 1/6 + 20/60
= 21/30

Average Speed = 28 * 30 / 21
= 40 miles/ hr

A

bumpbot · Answer

Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.

Jerry travels 8 miles at an average speed of 40 miles per hour, stops

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

Jerry travels 8 miles at an average speed of 40 miles per hour, stops

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards