Percentages

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HSPT Math › Percentages

Questions 1 - 10

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?

$425\ students$

$75\ students$

$85\ students$

$450\ students$

$325\ students$

Explanation

If 15% of students ordered fish, then 85% of the students must have ordered chicken. Then multiply 85% or $.85\times 500 = 425$ .

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?

$425\ students$

$75\ students$

$85\ students$

$450\ students$

$325\ students$

Explanation

If 15% of students ordered fish, then 85% of the students must have ordered chicken. Then multiply 85% or $.85\times 500 = 425$ .

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

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 .

$=\frac{25}{100}$

We can simplify this fraction: $\frac{25}{100}=\frac{5}{20}=\frac{1}{4}$ .

Either way, we get the same answer.

What number increased by 25% is equal to 7?

$5 \frac{3}{5}$

$5\frac{1}{4}$

$5\frac{5}{6}$

$4\frac{2}{3}$

Explanation

To increase a number by 25% is to take

of the number, or, equivalently, multiply it by

$\frac{125}{100} = \frac{125 \div 25 }{100 \div 25 } = \frac{5}{4}$ .

Therefore, we divide 7 by $\frac{5}{4}$ :

$7 \div \frac{5}{4} = \frac{7 }{1}\div \frac{5}{4} = \frac{7 }{1}\times \frac{4} {5}= \frac{7\times 4 }{1\times 5} = \frac{28}{5}$

$28 \div 5 = 5 \textup{ R }3$ , so

$\frac{28}{5} = 5 \frac{3}{5}$ .

If sales tax on a pair of jeans is , and the jeans cost $\$ 50$ 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 $ $\small 50$ , we must first find $\small 16$ % of $ $\small 50$ . In order to do that we multiply $ $\small 50$ by the decimal form of $\small 16$ %, which is $\small .16$ .

Note: In order to find the decimal form of a percent, we divide it by $\small 100$ . $\small 16/100 = .16$

Find the tax:

$\small .16\cdot 50 = 8$

Therefore the sales tax added to the original price is $ $\small 8$ .

$\small 50+8= 58$

The final cost of the jeans is $ $\small 58$ .

If sales tax on a pair of jeans is , and the jeans cost $\$ 50$ before tax, what is the final price of the jeans including tax?

\$58

\$66

\$56

\$60

\$62

Explanation

Note: In order to find the decimal form of a percent, we divide it by $\small 100$ . $\small 16/100 = .16$

Find the tax:

$\small .16\cdot 50 = 8$

Therefore the sales tax added to the original price is $ $\small 8$ .

$\small 50+8= 58$

The final cost of the jeans is $ $\small 58$ .

A class has 25 students. If 60% of them are boys, how many students are girls?

Explanation

We know that 40% of the class are girls because 60% are boys. To express 40% as a fraction of the 25 total students, we set up a proportion to find the number of girls in the class.

$\frac{40}{100} = \frac{x}{25}$

$\frac{2}{5}=\frac{x}{25}$

When solving for , we find that there are 10 girls in the class.

A restaurant is having a sale and lowering their prices by 20%. If an average meal for two normally costs \$62.00, what will it costs under the current sale?

$\$49.60$

$\$82.00$

$\$42.00$

$\$50.00$

Explanation

Multiply:

Then, subtract that amount from the original price:

Answer: \$49.60

A class has 25 students. If 60% of them are boys, how many students are girls?

Explanation

We know that 40% of the class are girls because 60% are boys. To express 40% as a fraction of the 25 total students, we set up a proportion to find the number of girls in the class.

$\frac{40}{100} = \frac{x}{25}$

$\frac{2}{5}=\frac{x}{25}$

When solving for , we find that there are 10 girls in the class.

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