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A man walks from B to C, a distance of x miles, at 8 miles per hour an 24 Jan 2016, 06:37
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A man walks from B to C, a distance of x miles, at 8 miles per hour and returns at 12 miles per hour. What is his average speed?

A. 10 mph
B. 9.6 mph
C. 8.8 mph
D. 8.4 mph
E. 4 mph
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B
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A man walks from B to C, a distance of x miles, at 8 miles per hour an 24 Jan 2016, 07:51
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D= Distance between B and C

Time to cover the round trip = D/8 + D/12 = 5D/24

Total Distance covered = 2D

Avg Speed = Total Distance / Total Time
=2D*24/5D
=9.6 mph

Answer: B
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A man walks from B to C, a distance of x miles, at 8 miles per hour an 24 Jan 2016, 08:04
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Total distance covered = 2x
Time taken 12 miles / hour = x/12 hrs
Time taken @ 8 miles / hour = x/8 hrs



Avg speed = 2x / (x/8 + x/12) = 9.6 mph
Ans is B
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A man walks from B to C, a distance of x miles, at 8 miles per hour an 24 Jan 2016, 08:37
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Please be careful don't follow the formula (a+b)/2 as this is a case of weighted average
A simple approach would be consider
Take LCM of the avg speeds given i.e. of 8 and 12 which would be 24
Now suppose the distance from B to C as 24 then total distance would be 24*2=48
Similarly,
Time=Distance/Speed so, Total Time = 24/8+24/12=5 hrs
Now,
Avg Speed=Total Distance/Total Time=48/5=9.6
Hence the answer is B

Please consider a kudos if this was helpful :-D
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A man walks from B to C, a distance of x miles, at 8 miles per hour an 27 Mar 2016, 13:29
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just use the formula (2*s1*s2)/(s1+s2) as avrage speed will be independant of the distance x.
s1 - speed of going from b to c = 8mph
s2 - speed of going from c to b = 12mph
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A man walks from B to C, a distance of x miles, at 8 miles per hour an 03 Apr 2019, 18:07
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Bunuel
A man walks from B to C, a distance of x miles, at 8 miles per hour and returns at 12 miles per hour. What is his average speed?

A. 10 mph
B. 9.6 mph
C. 8.8 mph
D. 8.4 mph
E. 4 mph
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We can use the formula:

average = (total distance)/(total time)

average = 2x/(x/8 + x/12)

average = 2x/(3x/24 + 2x/24)

average = 2x/(5x/24)

average = 48x/(5x) = 9.6

Answer: B
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A man walks from B to C, a distance of x miles, at 8 miles per hour an 24 May 2021, 00:43
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assume x= 48

48*2/(10)= 9.6
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A man walks from B to C, a distance of x miles, at 8 miles per hour an 05 Jan 2024, 13:19
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