# Percent Tips and Tricks plus Practice Questions

- Posted by Brian Stocker MA
- Date March 27, 2014
- Comments 4 comments

### Percent

Below are percent practice questions similar to what you will find on a standardized test. A variety of different types of questions is given – some may be classified as number manipulation, word problems, arithmetic reasoning.

If you can do these problems, you should have no trouble doing percent questions on a standardized test!

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### Percent Tips, Tricks and Shortcuts

Percent problems are not nearly as scary as they appear, if you remember this neat trick:

- Draw a cross like so:

# **+**

- In the upper left, write PORTION. In the bottom left write WHOLE. In the top right, write PERCENT and in the bottom right, write 100. Whatever your problem is, you will leave blank the unknown, and fill in the other four parts. For example, let’s suppose your problem is: Find 10% of 50. Since we know the 10% part, we put 10 in the percent corner. Since the whole number in our problem is 50, we put that in the corner marked whole. You always put 100 underneath the percent, so we leave it as is, which leaves only the top left corner blank. This is where we’ll put our answer.Now simply multiply the two corner numbers that are NOT 100. In this case, it’s 10 X 50. That gives us 500. Now multiply this by the remaining corner, or 100, to get a final answer of 5. 5 is the number that goes in the upper-left corner, and is your final solution.
- Another hint to remember: Percents are the same thing as hundredths in decimals. So .45 is the same as 45 hundredths or 45 percent.

### Converting Percents to Decimals

Percents are simply a specific type of decimals, so it should be no surprise that converting between the two is actually fairly simple. Here are a few tricks and shortcuts to keep in mind:

- Remember that percent literally means “per 100” or “for every 100.” So when you speak of 30% you’re saying 30 for every 100 or the fraction 30/100. In basic math, you learned that fractions that have 10 or 100 as the denominator can easily be turned into a decimal. 30/100 is thirty hundredths, or expressed as a decimal, .30.
- Another way to look at it: To convert a percent to a decimal, simply divide the number by 100. So for instance, if the percent is 47%, divide 47 by 100. The result will be .47. Get rid of the % mark and you’re done.
- Remember that the easiest way of dividing by 100 is by moving your decimal two spots to the left.

### Converting Percent to Fractions

Converting percents to fractions is easy. After all, a percent is nothing except a type of fraction; it tells you what part of 100 that you’re talking about. Here are some simple ideas for making the conversion from a percent to a fraction:

# **+**

- If the percent is a whole number — say 34% — then simply write a fraction with 100 as the denominator (the bottom number). Then put the percentage itself on top. So 34% becomes 34/100.
- Now reduce as you would reduce any percent. In this case, by dividing 2 into 34 and 2 into 100, you get 17/50.
- If your percent is not a whole number — say 3.4% –then convert it to a decimal expressed as hundredths. 4 is the same as 3.40 (or 3 and forty hundredths). Now ask yourself how you would express “three and forty hundredths” as a fraction. It would, of course, be 3 40/100. Reduce this and it becomes 3 ⅖.

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### Practice Questions

**1. 15 is what percent of 200?**

a. 7.5%

b. 15%

c. 20%

d. 17.50%

**2. A boy has 5 red balls, 3 white balls**

** and 2 yellow balls. What percent of the**

** balls are yellow?**

a. 2%

b. 8%

c. 20%

d. 12%

**3. Add 10% of 300 to 50% of 20**

a. 50

b. 40

c. 60

d. 45

**4. Convert 75% to a fraction.**

a. 2/100

b. 85/100

c. 3/4

d. 4/7

**5. Multiply 3 by 25% of 40.**

a. 75

b. 30

c. 68

d. 35

**6. What is 10% of 30 multiplied by 75% of 200?**

a. 450

b. 750

c. 20

d. 45

**7. Convert 4/20 to percent.**

a. 25%

b. 20%

c. 40%

d. 30%

**8. Convert 0.55 to percent.**

a. 45%

b. 15%

c. 75%

d. 55%

**9. What number is the largest? **

a. 5 % of 400

b. 25% of 4000

c. 2 % of 500

d. 8% of 1000

**10. In a class of 83 students, 72 are present. What percentage of the students are absent? Provide answer up to two significant digits.**

a. 12

b. 13

c. 14

d. 15

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### Answer Key

**1. A**

15/200 = X/100

200X = (15 * 100)

1500/200 Cancel zeroes in the numerator and denominator 15/2 = 7.5%.

Notice that the questions asks, What 15 is what percent of 200? The question does **not** ask, what is 15% of 200! The answers are very different.

**2. C**

Total no. of balls = 10, no. of yellow balls =

2, answer = 2/10 X 100 = 20%.

**3. B**

10% of 300 = 30 and 50% of 20 = 10 so 30 + 10 = 40.

**4. C**

75%= 75/100 = 3/4

**5. B**

25% of 40 = 10 and 10 x 3 = 30

**6. A**

10% of 30 = 3 and 75% of 200 = 150, 3 X

150 = 450

**7. B**

4/20 X 100 = 1/5 X 100 = 20%

**8. D**

0.55 X 100 = 55%

**9. B
**Here are the choices:

a. 5% of 400 = 20

b. 25% of 4000 = 1000

c. 2% of 500 = 10

d. 8% of 1000 = 80

B is the largest.

**10. B
**Absent students = 83 – 72 = 11

Percentage of absent students = 11/83 X 100 = 13.25

Reducing up to two significant digits it will be 13.

### Common Percent Mistakes on a Test

**Errors in Percent Increase and Decrease:**

Don’t confuse the value with the change. For example, a 20% increase of $100 ($20) so the new value is $120, not $20.

**Errors Converting Percentages to Decimals **

When converting a percentage to a decimal you divide by 100. For example, 20% as a decimal is 0.20.

**Errors in Units and Context**

Not paying attention to what the percentage is of. For example, 20% of 50 is not the same as 50% of 20.

**Confusing Percentage Points with Percent Change**

For example, an increase from 10% to 15% is a 5 **percentage point** increase, and a 50% **percent change**.

**Not Converting the Final Answer**

Forgetting to convert the final answer back to a percentage if needed, or not expressing the answer in the format the question asks.

**Written by**, Brian Stocker MA., Complete Test Preparation Inc.

**Date Published:**Thursday, March 27th, 2014

**Date Modified:**Thursday, June 27th, 2024

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## 4 Comments

I was just taking the test for fun I wanted to see if I was still good with my knowledge of percents and I got 11 right and 7 wrong. I’m so glad I did the test thank you and I will continue to practice.

thanks a lot this practice is very useful ; it helped me review for my exam.

Mistakes to avoid very helpful – I printed out for my class! thanks

Thanks! i confuse percent change and percent points