What is the length of the shortest log?

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nickolhomero: Newbie | Next Rank: 10 Posts; Posts: 6; Joined: Fri May 01, 2009 1:52 pm

What is the length of the shortest log?

by nickolhomero » Fri May 01, 2009 2:01 pm

I ran into the following problem, found in the mba.com prep test. Can someone please explain why 100 is the answer?

The average of 5 logs is 124 cm. What is the length of the shortest log?

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Source: Beat The GMAT — Problem Solving | Fri May 01, 2009 2:01 pm

DanaJ: Site Admin; Posts: 2567; Joined: Thu Jan 01, 2009 10:05 am; Thanked: 712 times; Followed by:550 members; GMAT Score:770

by DanaJ » Sat May 02, 2009 11:11 pm

Say l1, l2, l3, l4 and l5 are the lengths of your logs.

You know that their average is 124, meaning that (l1 + l2 + l3 + l4 + l5)/5 = 124. This means that:

l1 + l2 + l3 + l4 + l5 = 5*124 = 620.

HOWEVER, your problem is missing something, like for instance if the lengths of logs follow a specific progression. With just the info provided, you could very well say that you have l1 = 1, l2=l3=l4=124 and l5 = 247.