GMAT Problem Solving (PS) | Word Problem - Five friends Alastair, Bell, Cook, Darren and Eoin appe

Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an aptitude test. Alastair scored exactly\(\frac{1}{2}\) of Darren’s score, whose score was\(\frac{1}{5}\) th more than Cook’s score. Eoin scored\(\frac{2}{5}\) th more than Cook and Darren’s score was\(\frac{3}{2}\)  times that of Bell’s score. If the average score (arithmetic mean) of the group was 50, what was the range of the scores of the group?

A.25
B.30
C.35
D.40
E.50

the 5 scores form a progression:
C-2/5, C-1/5, C, C+1/5,
...

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