Lesson: Finding x Percent of y

Comment on Finding x Percent of y

Sir, the way you teach and your explanation are so clear and interesting that makes math fun for non math student like me.Kudos to you and your teaching.

HI BRENT,can u pls explain this problem
If a ticket increased in price by 20%, and then increased again by 5%, by what
percent did the ticket price increase in total?

gmat-admin's picture

Sure thing!

Let's say the ORIGINAL ticket price is $100

After a 20% increase, the new ticket price is $120 ($100 + 20% of $100 = $100 + $20 = $120)

After a 5% increase, the FINAL ticket price is $126 ($120 + 5% of $120 = $120 + $6 = $126)

If the ORIGINAL price was $100 and the FINAL price is $126, then the price increase is 26%

After solving some question I feel like always x or whole comes after of . So it okay presume the same .
gmat-admin's picture

I'm leery about saying "always," but I can't think of an example where the "whole" does not come after the word "of"

If course there are questions like "What is 10% of 40% of 60?" but after we calculate 40% of 60, we basically treat it like a new "whole."

If the total payroll expense of a certain business in year Y was $84,000, which was 20 percent more than in year X, what was the total payroll expense in year X ?

(A) $70,000

(B) $68,320

(C) $64,000

(D) $60,000

(E) $52,320
It's a easy question but I don't know what I doing . I used x /84000= 20/100 . What method should I use
gmat-admin's picture

If K is 20% more than W, we can write: K = 1.20W

So, with this question, we're told that year Y's payroll expenses (of $84,000) is 20% more than in year X's expenses.

So, we can write: (year Y's payroll expenses) = 1.20(year X's payroll expenses)

In other words, $84,000 = 1.20(year X's payroll expenses)

Divide both sides by 1.20 to get: $84,000/1.20 = year X's payroll expenses

Evaluate: $84,000 = year X's payroll expenses

Answer: A

In a certain furniture store, each week Nancy earns a salary of $240 plus 5% of the amount of her total sales that exceeds $800 for the week. If Nancy earned a total of $450 one week, what were her total sales that week ?

A. $2,200
B. $3,450
C. $4,200
D. $4,250
E. $5,000
I used eliminating method I choose 5000-800. 4200 *5/100 for 210 then 450-240 gives 210 . This tell us it was right . How will I use your method in this
gmat-admin's picture

Let x = total sales

Nancy gets 5% commission on sales that exceed $800

So, commission = 5% of (x - 800)

This means TOTAL SALARY = $240 + 0.05(x - 800)

We get: $450 = $240 + 0.05(x - 800)

Subtract 240 from both sides: 210 = 0.05(x - 800)

Divide both sides by 0.05 to get: 4200 = x - 800

So, x = 5000

damn it. forgot to do the x-800 bit

In the united states 13 out of every 20 can recycled.

What percent of Cans are recycled?

pls help me understand above ques.. https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-ratios-prop-topic/cc-6th-percent-word-problems/e/percentage_word_problems_1
gmat-admin's picture

I'm not sure which question you'd like me to answer, so I'll do both.

QUESTION 1: In the united states 13 out of every 20 can recycled. What percent of Cans are recycled?
Part/Whole = 13/20 = 65/100 = 65%

QUESTION 2 (at https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-ratios-prop-...): An estimated 3 out of every 25 men are left-handed. What percent of men are left-handed?
Part/Whole = 3/25 = 12/100 = 12%


Hi Brent, I need some basic help here... In the following question, I'm never sure how to properly derive 1.15 and my tendency is to go to 0.85 instead. Here's the question: "Company P had 15 percent more employees in December than it had in January. If Company P had 460 employees in December, how many employees did it have in January?" Can you please help me see how to derive "250/1.2"?
A similar step can be found on Q210 of PS in the OG 2020.
gmat-admin's picture

Question link: https://gmatclub.com/forum/company-p-had-15-percent-more-employees-in-de...

I have no idea where the 250/1.2 comes in. I don't see how we'd get to that point. I also don't see any solutions that require that calculation.
Can you show me more of the solution that mentions 250/1.2?

In the meantime, here's my full solution: https://gmatclub.com/forum/company-p-had-15-percent-more-employees-in-de...


Yulia's picture

Hi Brent,

Please explain me something.

6.4 is what percent of 16,000?

A) 0.0004%
B) 0.04%
C) 0.4%
D) 4%
E) 4.4%

What I did
x/100 * 16000 = 6.4
160x =6.4
x= 6.4/160
x=4/100>>> So I though that the answer is 4% because x= 4/100.

What am i missing?
gmat-admin's picture

Question link: https://gmatclub.com/forum/6-4-is-what-percent-of-105302.html#p1996182

In your solution x = the desired PERCENT
This is why you converted x percent to x/100

So, if x = 4/100, then the desired percent is (4/100)% (aka 0.04%)

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