The manufacturer of Sleep-EZ mattresses is offering

Let the current retail price = 100.

1st discount = 10%. Hence New price = 90.

2nd discount = 20% on New price., Hence, Final price = 90-18 = 72.

Hence, Net discount on the original price is 28%. Hence, C
_________________

If we REDUCE a price by 10%, then the reduced price is 90% of the original price.
Likewise, if we REDUCE a price by 20%, then the reduced price is 80% of the original price.
If we REDUCE a price by 30%, then the reduced price is 70% of the original price.
.....etc.
----------------------------------

Let $100 be the original price.
So, a 10% reduction means the new price = (0.9)(100) = $90
A further 20% reduction means the new price = (0.8)(0.9)(100) = $72
This represents a $28 discount off the original $100
28/100 = 28%

Answer:

RELATED VIDEO

_________________

Two methods to solve this one =>
Let CP be x => SP=x[1-10/100][1-20/100]=72x/100
discount amount = x=72x/100=28x/100
Discount percent = discount/CP *100 = 28%
Smash that C


Method 2 =>
Let CP=100
SP=100[1-10/100][1-20/100]=72
hence Discount = 28
Discount percent = 28%
_________________

Discount = 1-0.9*0.8=1-0.72=0.28=28%
Answer choice C.

This is an example in the lower range that wants to trick people into forgetting about the joint effect of the two discounts and thus simply adding them to get 30%.
_________________

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________