Problem Solving

54. Two people walked the same distance, one person's speed is between 25 and 45,and if he used 4 hours, the speed of another people is between 45 and 60,and if he used 2 hours, how long is the distance?
A.116
B.118
C.124
D.136
E.140

Solution: Considering the speed of the two persons.

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First Approach
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Distance traveled within 4 hours will be within the range
= 25*4 - 45*4
=100 - 180

Second person -
Distance traveled within 2 hours will be within the range
= 45*2 - 60*2
=90 - 120

Options A and B satisfy these conditions

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Second Approach
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First person -
=average speed*hours travelled
= (2*V1*V2) / V1 + V2
=128.5

Similarly, for second person:
~103

To decide between the options, I just took out the average of these two values.

=129 + 103 / 2 = 116

I am just wondering whether taking out the average of the two values is the correct thing to do....