We are told :

All 3 students (s1, s2 and s3) scored between 500 and 750 in all the tests

Ranges of each : R1 = 50, R2 = 80 and R3 = 120

Max possible range :

Let’s say s1 scored 500 in one test and his range is 50

So he scored between 500 and 550 in all the tests

Say s2 scored 750 in one test and his range is 120

So he scored between 630 and 750 in all the tests

Third person is irrelevant in this case we have max and min value of their scores

So, Max. possible range = 750 – 500 = 250

Min Possible range :

Lets say s1 scored 750 in one test and his range is 120

So he scored between 630 and 750 in all the tests

Both of the other person can score between 630 and 750 and still be within their range of 80 and 50.

Min range can be 750-630 = 120

So, the difference between Max and Min range = 250 – 120 = 130

Option E

_________________

Compilation of Blogs by Mike Mcgarry - Magoosh