X is the average price of 10 items of which no two cost the same. If each of the cheapest 5 items loses 10% in price while each of the most expensive 5 items gains 10% in price, which of the following is possible about ?
I. X will decrease
II. X will not change
III. X will increase
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
Mean Changes
This topic has expert replies
-
gmatboost
- Master | Next Rank: 500 Posts
- Posts: 312
- Joined: Tue Aug 02, 2011 3:16 pm
- Location: New York City
- Thanked: 130 times
- Followed by:33 members
- GMAT Score:780
Each change is 10% of the previous price.
The 5 increases are EACH bigger than ANY of the 5 decreases, since the increases are taken from LARGER initial amounts.
This means the total increase > total decrease, so X goes up.
The 5 increases are EACH bigger than ANY of the 5 decreases, since the increases are taken from LARGER initial amounts.
This means the total increase > total decrease, so X goes up.
Greg Michnikov, Founder of GMAT Boost
GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.
Also, check out the most useful GMAT Math blog on the internet here.
GMAT Boost offers 250+ challenging GMAT Math practice questions, each with a thorough video explanation, and 100+ GMAT Math video tips, each 90 seconds or less.
It's a total of 20+ hours of expert instruction for an introductory price of just $10.
View sample questions and tips without signing up, or sign up now for full access.
Also, check out the most useful GMAT Math blog on the internet here.
If A is the sum of the cheapest items and B the sum of the most expensive items, then
A decrease of 10% in A and an increase of 10% in B would result in a value change of the average as follows
X + 10% (B-A) which is a positive number since B>A
X will therefore increase
A decrease of 10% in A and an increase of 10% in B would result in a value change of the average as follows
X + 10% (B-A) which is a positive number since B>A
X will therefore increase
