Percentages

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HSPT Math › Percentages

Questions 1 - 10
1

Which of the following operations is equivalent to taking of a number?

Dividing the number by

Dividing the number by

Dividing the number by

Moving the decimal point one place to the left, then doubling the result

Moving the decimal point one place to the left, then tripling the result

Explanation

Let's just pick a number at random, for example .

of this number is , which is divided by .

We can also work by simplifying the fractional form of . A percent can be written as the number divided by .

We can simplify this fraction: .

Either way, we get the same answer.

2

Which of the following operations is equivalent to taking of a number?

Dividing the number by

Dividing the number by

Dividing the number by

Moving the decimal point one place to the left, then doubling the result

Moving the decimal point one place to the left, then tripling the result

Explanation

Let's just pick a number at random, for example .

of this number is , which is divided by .

We can also work by simplifying the fractional form of . A percent can be written as the number divided by .

We can simplify this fraction: .

Either way, we get the same answer.

3

There are 500 students at the high school. There are only two menu options: chicken or fish. If 15% of students ordered fish, how many students ordered chicken?

Explanation

If 15% of students ordered fish, then 85% of the students must have ordered chicken. Then multiply 85% or .

4

What number increased by 25% is equal to 7?

Explanation

To increase a number by 25% is to take

of the number, or, equivalently, multiply it by

.

Therefore, we divide 7 by :

, so

.

5

If sales tax on a pair of jeans is , and the jeans cost before tax, what is the final price of the jeans including tax?

$58

$66

$56

$60

$62

Explanation

Since the jeans are the only item being purchased, and they cost $, we must first find % of $. In order to do that we multiply $ by the decimal form of %, which is .

Note: In order to find the decimal form of a percent, we divide it by .

Find the tax:

Therefore the sales tax added to the original price is $.

The final cost of the jeans is $.

6

What number increased by 25% is equal to 7?

Explanation

To increase a number by 25% is to take

of the number, or, equivalently, multiply it by

.

Therefore, we divide 7 by :

, so

.

7

For her birthday, Susan asks her mother to buy her a car. Susan’s mother agrees to give Susan 150 percent of whatever amount Susan can save up in six months. If Susan saves , how much does Susan’s mother owe her?

$900

$750

$300

$700

$550

Explanation

When Susan's mother agreed to match her savings plus fifty percent, she agreed to give Susan % plus %.

Before multiplying by the amount Susan saved, we must convert % to a decimal by dividing by .

Now we multiply time $.

Susan's mother owes her $.

8

is one-third of , which is four-fifths of . What percent of is ?

Explanation

is four-fifths of , so .

is one-third of , so

is of ; the percent equivalent is that is

of

9

Write as a decimal.

Explanation

To convert a percentage into a decimal, divide the number by 100.

Here's a trick: Simply pretend there is a decimal point at the end of the number, and then move the decimal point two places to the left.

You can think of 42 as 42.0 (or 42. - the zero doesn't matter). Now move the decimal point two places to the left.

Answer:

10

Which is larger?

a. 10% of 90

b. 5% of 160

c. 20% of 50

d. 30% of 40

Explanation

First find the percentage amount for each choice by multiplying the number by the percentage amount

a.

b.

c.

d.

Then compare the amounts to find the largest.

The answer is (d) 12.

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