A car traveled from San Diego to San Francisco at an average speed of

Question

A car traveled from San Diego to San Francisco at an average speed of 48 miles per hour. If the journey back took twice as long, what was the average speed of the trip?

A. 24.
B. 32.
C. 36.
D. 42.
E. 44.

Kurtosis · Answer

Let the time taken be = x

One way distance = 48x
Total distance traveled = 2 * 48x = 96x
Total time taken = x + 2x = 3x

Average speed = 96x/3x = 32

Answer: B

CounterSniper · Answer

another way of doing this !!

let s1 and s2 be the speed 
and 
let t1 and t2 be the time taken by the car to travel the respective distances

as per the question
t1/t2=1/2

now since speed is inversely proportional to time

s1/s2=2/1
therefore s2 = 24

average speed for the trip = 2s1s2/s1+s2
or,
2*48*24/72= 32 B

nightblade354 · Answer

-- 48 miles per hour, so let's say the trip took 1 hour (traveled 48 miles there, and 48 miles back)
-- Trip took 2 hours coming back, because it is twice as long
-- Equation: speed = distance/time d = 96, t = 3; 96/3 = 32

Mansoor50 · Answer

my first attempt was a follows:

d is the distance and t is the time at 48mph --> d=48t --> t=d/48

since it took twice as long on the way back, means the speed is 24 mph
this means: d=24(2t)--> d=48t --> t=d/48

avg speed is total distance/total time --> 2d/(d/48+d/48) giving an answer of 48 mph

can anyone point out flaw in my logic?

testcracker · Answer

another way to looking into the problem, and in fact, I have tried the problem this way

since, the "journey back" took twice as long, then, the the speed of "journey back" was half that of "journey to"

thus, since the speed of "journey to" was 48 mph, the speed of "return" was 24 mph

and, since, the distance is same, harmonic mean can be applied to averaging the speed

2 x 48 x 24
___________
 48 + 24

= 32 = B, the answer

thanks and cheers

Kinshook · Answer

Given: A car traveled from San Diego to San Francisco at an average speed of 48 miles per hour. 
Asked: If the journey back took twice as long, what was the average speed of the trip?

Let the distance between San Diego to San Francisco be 480 miles
Total distance = 480 *2 = 960 miles
Total time taken = 10 + 20 = 30 hours
Average speed = 960 / 30 = 32 mph

IMO B

Archit3110 · Answer

onward journey speed 48 mph
and rtrn speed ; 24mph because time taken is twice so speed must be half of onward 
avg speed ; 2 *48*24/72 
option B 32

EgmatQuantExpert · Answer

Given

• A car traveled from San Diego to San Francisco at an average speed of 48 miles per hour.
• Travelling back took twice as long.

To Find

• The average speed.

Approach and Working Out

• Speed of the forward journey = 48 mph.
• Speed while coming back = 48/2 = 24mph.
 o The time taken is double so speed will be half. 
• Let the distance be a common multiple of 48 and 24 = 48k miles.
 o Time taken for forward journey= 48k/48 = k hours.
o Time taken for coming back = 48k/24 = 2k 
• Total distance = 48k + 48k = 96 k
• Total time = 3k
 o Average speed = 96k/3k = 32.

Correct Answer: Option B

A car traveled from San Diego to San Francisco at an average speed of

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A car traveled from San Diego to San Francisco at an average speed of

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