GmatKiss wrote:Foodmart customers regularly buy at least one of the following products: milk, chicken, or apples. 60% of shoppers buy milk, 50% buy chicken, and 35% buy apples. If 10% of the customers buy all 3 products, what percentage of Foodmart customers purchase exactly 2 of the products listed above?
a. 5%
b. 10%
c. 15%
d. 25%
e. 30%
OA after sometime
Here is the formula for 3 overlapping groups in which sometimes 2 groups overlap and sometimes all 3 groups overlap:
T = G1 + G2 + G3 - (those in 2 of the groups) - 2*(those in all 3 groups)
The big idea with overlapping groups is to
subtract the overlaps. When we count everyone in the 3 groups, those in 2 of the groups will be counted twice, so they need to subtracted from the total
once. Those in all 3 groups will be counted 3 times, so they need to be subtracted from the total
twice.
In the problem above:
T = 100.
G1+G2+G3 = milk + cheese + apples = 60+50+35 = 145.
Those buy exactly 2 products = x.
Those who buy all 3 products = 10.
Plugging these values into the formula, we get:
100 = 145 - x - 2*10
x = 25.
The correct answer is
D.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at
[email protected].
Student Review #1
Student Review #2
Student Review #3
