Hi,

It’s a straight forward question.

Given,

Distance between A and B is 240 miles.

Bob travels from city A to city B and returns by the same route.

So, total distance he travelled is 480 miles.

Question:

Was Time taken for the entire journey is less than 13 hours ?

We know that,

Time taken = total distance / Speed.

Statement I is sufficient:

The speed during the entire journey varied between 20 mph and 36 mph.

Even if we take the highest speed in the above given range, still the total time taken would be more than 13 hours.

i.e.,

time taken = 480/ 36

= 13.333

So, it we take the speed further less, then time taken will be ofcourse more than 13.33hours.

Answer to the question is always NO.

So statement I is sufficient.

Statement II is sufficient:

The average speed was 30 mph.

We know that,

Average speed = total distance / total time taken

30 = 480/ total time taken

Time taken = 16 hours.

Again answer to the question is NO.

So sufficient.

So the answer is D.

Hope this helps.

Regards,

Junaid.

Byjus GMAT Quant Expert

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