75% of the guestrooms at the Stagecoach Inn have a queen-siz

Hi thanks for the answer.

I am not able to understand as how from 10% you have calculated 0.4X or 25%. Can you please answer.

The rightmost columns and the bottom rows are the sums of preceding boxes.

Since 75% of the rooms have a queen-sized bed, and each of the remaining rooms has a king-sized bed, the the percentage of the rooms that have a king-sized bed is 100-75=25.

Similarly, if x is the percentage of non-smoking rooms and 60% of that or 0.6x is non-smoking rooms with a queen-sized bed, then x-0.6x=0.4x is the percentage of non-smoking rooms with a king-sized bed.

Hope it's clear.

Let total number of rooms be 100.

Then number of rooms with
king size: 25
queen size: 75

10 % of total are rooms with king size and non-smoke = 10 Rooms.
60 % of non-smoke rooms have queen size. So the rest (40 %) must have a king size bed. This means that 10 non smoking rooms are 40 % of non-smoking rooms, hence 60 % of non smoking rooms are 15 rooms. This means that 25 rooms are non smoking rooms and 75 are smoking rooms. The answer is E.

Question is quite wordy...for a non native speaker difficult to understand.

Refer diagram below:

Say total rooms = 100

We require to find value of "x" (Shaded in Green)

Setting up equation from values calculated in table

\(\frac{60}{100} (100-x) + 10 = 100-x\)

x = 75%

Answer = E

Information about no of queen & king size beds is of no use for the solution.

OFFICIAL SOLUTION

This is an overlapping sets problem, which can be solved most efficiently by using a double set matrix. Our first step in using the double set matrix is to fill in the information given in the question. Because there are no real values given in the question, the problem can be solved more easily using 'smart numbers'; in this case, we can assume the total number of rooms to be 100 since we are dealing with percentages. With this assumption, we can fill the following information into our matrix:

There are 100 rooms total at the Stagecoach Inn.

Of those 100 rooms, 75 have a queen-sized bed, while 25 have a king-sized bed.

Of the non-smoking rooms (let's call this unknown n), 60% or .6n have queen-sized beds.

10 rooms are non-smoking with king-sized beds.

Let's fill this information into the double set matrix, including the variable n for the value we need to solve the problem:

In a double-set matrix, the first two rows sum to the third, and the first two columns sum to the third. We can therefore solve for n using basic algebra:

10 + .6n = n
10 = .4n
n = 25

We could solve for the remaining empty fields, but this is unnecessary work. Observe that the total number of smoking rooms equals 100 – n = 100 – 25 = 75. Recall that we are working with smart numbers that represent percentages, so 75% of the rooms at the Stagecoach Inn permit smoking.

The correct answer is E.

let the total rooms be 100
no. of queen sized bedroom = 75
no. of king sized bedroom = 25
let the non smoking room be x
smoking room = 100-x
queen sized non smoking = 0.6x
according to later statement no. of king sized non smoking = 10
king sized non smoking = 0.4x = 10
x = 25

smoking rooms = 75
percentage = 75/100 * 100 = 75%

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.