GMATPrep Question 18

gurudev · Posted: Thu Sep 04, 2008 12:19 pm Post subject: GMATPrep Question 18

Please help me!! not able to get the explanation!!

parallel_chase · Posted: Thu Sep 04, 2008 1:23 pm Post subject:

Store Sold 90 copies last week.

greatest number of copies = saturday
second greatest number of copies = friday

Statement I

8 copies sold on thursday

90-8 = 82

15 copies were sold monday, tuesday and wednesday
15*3 = 45
82-45 = 37
friday = 18 copies
saturday = 19 copies

9 copies were sold on monday, tuesday and wednesday
9*3=27
82-27 =55
friday = 10 copies
saturday = 45 copies

Therefore insufficient.

Statement II

38 copies were sold on saturday.

90-38=52

10 copies were sold on monday, tuesday, wednesday, thursday

10*4=40

at least 12 copies were sold on friday

11 copies were sold on monday, tuesday, wednesday, thursday
11*4 =44

52-44 = 8 copies sold on friday, this cannot be possible since friday has to be second greatest.

Therefore sufficient.

Hence B is the answer.

4meonly · Posted: Fri Sep 05, 2008 6:13 am Post subject:

I think answer is E because different number of books was sold.
Even combining we have that except Thu and Sat 46 books were sold
46 can be arranged in different ways among 5 days and with Fri the biggest.

We cannot assume that 10 copies were sold on monday, tuesday, wednesday, thursday
10*4=40
because we speak about different quantities on each day

What is OA?

gurudev · Posted: Fri Sep 05, 2008 7:39 am Post subject:

The OA is : B

Yes you are right that th equestion states to have different numbers also, it states a seven day week rather than a 6 day week.

I guess here it is that, how this is possible with B:
90-38=52. So 52 needs to be divided in 6 days.

Option 1: Friday 12(greater then 11)
gives 40 to be divided in 5 days, that makes an average of 8/day. It can be achieved by 6,7,8,9,10. Also it satisfies that Friday is second highest. If we take any other combination to make an average of 8 in 5 days, it will not give us Friday as the second highest.

Option 2: Friday 10(less then 12)
It gives us 42 to be divided in 5 days, that again makes out that any combination we try will not be able to make friday (10) as the second highest.

So, it is clear that Option 1 is true, so only B is sufficient. making that on Friday the number was greater then 11.....

With A: The picture is not clear about the highest number, so it can have N number of combinations and then Friday with second highest cane be greater then or less then 12....So not sufficient...

I hope now you are able to get the explanation right.....Hope it helps!!!

parallel_chase made some mistakes, but still managed to get the answer right, as the approach was correct and real good....thanks parallel_chase for making me understand the method.....