How to find a proportion

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SSAT Elementary Level Quantitative › How to find a proportion

Questions 1 - 10

What is of ?

Explanation

of is calculated by multiplying by .

$.10 \times 25=2.5$

Megan's teacher says that if Megan wants to join the girl's basketball team, she has to have at least of this quarter's homework turned in. If there have been assignments so far this quarter, how many of these does Megan have to have turned in so that she can join the team?

$45\ \text{assignments}$

$35\ \text{assignments}$

$30\ \text{assignments}$

$47\ \text{assignments}$

$27\ \text{assignments}$

Explanation

In order to solve this problem, we need to make a ratio. Megan's teacher says she needs to have turned in 90% of her homework. First we need to change 90% into a fraction:

$\frac{90}{100}$

Using this information, we need to fill in the following ratio to find out how many assignments Megan needs to have turned in to be at 90% completion:

$\frac{90}{100} =$ $\frac{?}{50}$

To solve this ratio, we need to cross multiply.

$90\times 50\ = 450$

Now we have an equation to solve.

$450 = 100\times \textup{?}$

If we divide both sides by 100, we are left with our final answer.

$450 \div 100 =: ?$

Megan must have at least 45 assignments turned in if she wants to join the basketball team.

Solve: $\frac{3}{7}= \frac{10}{x}$

$\frac{70}{3}$

$\frac{3}{70}$

$\frac{30}{7}$

$\frac{7}{30}$

$\frac{21}{10}$

Explanation

Solve by cross multipling the two fractions.

$3x=10\times7$

Divide by on both sides.

$x=\frac{70}{3}$

$Which;number;is;bigger: \frac{3}{7};or;\frac{3}{8},?$

$\frac{3}{7}$

$\frac{3}{8}$

Explanation

$For;example,;\frac{1}{2};is;bigger;than;\frac{1}{3}.$

A $\$75$ sweater is on sale for $\$45$ . What percentage of the original price has been discounted for the sale?

Explanation

Set up a proportion of the new price to the old price to see how they relate.

$\frac{$45}{$75} = \frac{3}{5}$ of the original price

Subtract $\frac{3}{5}$ from to find the amount that was discounted.

$1 - \frac{3}{5} = \frac{2}{5}$

Convert $\frac{2}{5}$ to a decimal by multiplying both the top and bottom of the fraction by , then convert to a percentage.

$\frac{2}{5} \times\frac{2}{2}=\frac{4}{10}$ , which is equivalent to or

What is of ?

Explanation

of is calculated by multiplying . by .

$.10\times 200=20$

Brad is paid $\$10$ per hour at his current job. If a promotion would increase Brad's pay by , what would Brad make per hour after a promotion?

$\$30$ per hour

$\$20$

$\$200$

$\$300$

$\$250$

Explanation

To find of Brad's pay, multiply it by (since is the original number and is twice that). $2 \times 10= 20$ , which is the amount of the increase to Brad's pay. Add this increase to the original pay to get the new pay: $$10 + $20 = \$30$ per hour.