For each month of a given year except December, a worker earned the same monthly salary and donated one-tenth of that salary to charity. In December, the worker earned N times his usual monthly salary and donated one-fifth of his earnings to charity. If the worker's charitable contributions totaled ...

Thanks Ron; this is helpful. Using your explanation, I think I can prove to myself in two ways that the value of S is irrelevant: 1) If you plug in S=10, the end of the calculation yields 3NS = 11S and the S's just cancel out, yielding N = 11/3. So S does not matter. 2) If you plug the N= 11/3 back ...

When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of the 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each y...

Thanks Ron. Very helpful.

Assume we have 6 chairs and 3 men and 3 women to fill them. For the following 4 questions, I have written down how I would calculate the answer using both combinatorics and the slot method. Can an instructor please confirm the logic and approach for each? Thank you! Q1: How many different ways can y...

The first time I took the GMAT, I selected 5 schools to view my score report. When I take it a second time, should I select the same 5 schools for them to be able to view my second score, or will they be able to view the second score anyway without me taking any action (i.e. should I use my 5 free s...

I recall reading somewhere in the Sentence Correction SG that the word "that" should be used after action verbs when connecting two clauses in a sentence; the reason is to reduce ambiguity. For example: "The students believed that they would make it to class on time." is preferre...

Ron, What about this problem/explanation from MGMAT CAT 6? It seems as if the answer explanation is stating that the "that" is necessary here. I'm trying to figure out if I should be removing any answers/looking for splits based on the word "that" in these types of examples. Than...