GMATPrep PS

This topic has expert replies
Legendary Member
Posts: 2789
Joined: Tue Jul 26, 2011 12:19 am
Location: Chennai, India
Thanked: 206 times
Followed by:43 members
GMAT Score:640

GMATPrep PS

by GmatKiss » Sat Oct 29, 2011 6:57 am
A grocer stacked oranges in a pile. The bottom layer was rectangular with 3 rows of 5 oranges each. In the second layer from the bottom, each orange rested on 4 oranges from the bottom layer, and in the third layer, each orange rested on 4 oranges from the second layer. Which of the following is the maximum number of oranges that could have been in the third layer?

o 5
o 4
o 3
o 2
o 1
Source: — Problem Solving |

Master | Next Rank: 500 Posts
Posts: 385
Joined: Fri Sep 23, 2011 9:02 pm
Thanked: 62 times
Followed by:6 members

by user123321 » Sat Oct 29, 2011 7:27 am
GmatKiss wrote:A grocer stacked oranges in a pile. The bottom layer was rectangular with 3 rows of 5 oranges each. In the second layer from the bottom, each orange rested on 4 oranges from the bottom layer, and in the third layer, each orange rested on 4 oranges from the second layer. Which of the following is the maximum number of oranges that could have been in the third layer?

o 5
o 4
o 3
o 2
o 1
With each layer one row and one column cease to exist.
so in third layer = (5-2)*(3-1) = 3
a max of three oranges are possible

is it C?

user123321
Just started my preparation :D
Want to do it right the first time.

Legendary Member
Posts: 2789
Joined: Tue Jul 26, 2011 12:19 am
Location: Chennai, India
Thanked: 206 times
Followed by:43 members
GMAT Score:640

by GmatKiss » Sat Oct 29, 2011 7:42 am
Not getting this. OA is C

User avatar
GMAT Instructor
Posts: 349
Joined: Wed Sep 28, 2011 3:38 pm
Location: Austin, TX
Thanked: 236 times
Followed by:54 members
GMAT Score:770

by GmatMathPro » Sat Oct 29, 2011 7:49 am
Picture the bottom 3x5 layer of oranges as follows:

OOOOO
OOOOO
OOOOO

The oranges in the next layer have to be resting in the middle of a set of four oranges. There are 8 "middles" like that where you could place an orange in the next level. If you place in orange in all of those, there are 8 oranges:

OOOO
OOOO

Now there are three "middles" or spots for oranges, so you could place a maximum of 3 oranges in that layer.
Pete Ackley
GMAT Math Pro
Free Online Tutoring Trial

Legendary Member
Posts: 2789
Joined: Tue Jul 26, 2011 12:19 am
Location: Chennai, India
Thanked: 206 times
Followed by:43 members
GMAT Score:640

by GmatKiss » Sat Oct 29, 2011 8:21 am
Very impressive explanation. Thanks a lot GmatMathPro :)