How to find percentage

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ISEE Middle Level Quantitative Reasoning › How to find percentage

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77% can also be writen as ________.

CORRECT

Explanation

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

Instead of doing long division, 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 77 as 77.0 (or 77. - the zero doesn't matter). Now move the decimal point two places to the left.

Answer:

What is 0.036 as a percent?

CORRECT

Explanation

Method 1:

Rewrite 0.036 as a fraction:

$\frac{36}{1000}$

Because percents are based on 100, divide the numerator and denominator by 10.

3.6%

Method 2:

Multiply $0.036 \times 100$

To multiply by 100, move the decimal point two places to the right; then add the percent sign:

3.6% is the correct answer.

A plane ticket is on sale for 25% its original price of \$300.00. What is the sale price of the plane ticket?

$\$225$

CORRECT

$\$75$

$\$325$

$\$275$

Explanation

First, multiply:

Then, subtract that amount from the original price:

Answer: The plane ticket is on sale for $\$225.00$

85 is what percent of 400?

$21 \frac{1 }{4} %$

CORRECT

$23 \frac{3}{4} %$

$27\frac{1}{2} %$

$19\frac{1}{2} %$

$22 \frac{1}{2} %$

Explanation

Set up the proportion statement, where is our answer, and solve:

$\frac{p}{100} = \frac{85}{400}$

$\frac{p}{100} \cdot 100 = \frac{85}{400} \cdot 100$

$p = \frac{85 \cdot 100}{400} = \frac{85 }{4} = 21 \frac{1 }{4} %$

Find the decimal equivalent of .

CORRECT

Explanation

To solve, divide:

$85\div 100=0.85$

Answer:

Convert to a decimal.

CORRECT

Explanation

Divide the percentage by 100, or move the decimal point two places to the left:

$57\div 100=.57$

Answer:

What is the decimal equivalent of ?

CORRECT

Explanation

Divide:

$43\div 100=0.43$

Answer:

There is a total of 50 houses in a neighborhood. 20 of the houses have red roofs and 15 of the houses have black roofs. The rest of the houses have green roofs. What percentage of the houses have green roofs?

CORRECT

Explanation

If there are a total of 50 houses and the total of red and black roofed houses is 35, there must be 15 green houses in this neighborhood.

$20\ \text{red}+15\ \text{black}=35$

$50\ \text{total} -35=15\ \text{green}$

To figure out what percentage a number makes up of any larger amount, divide the part by the whole. Since there are 15 green roofed houses, you should divide 15 by 50.

$\frac{\text{green}}{\text{total}}=\frac{15}{50}$

$\frac{15}{50} = 0.3$

When you multiply the decimal by 100, your result will be the percentage the smaller number makes up of the larger amount.

$0.3 \times 100 = 30$

Therefore, the answer is 30%

A computer is on sale for off its original price of $\$2400.00.$ What is the sales price of the computer?

CORRECT

Explanation

First, multiply

Then, subtract that amount from the original price:

Answer: The sales price is $\$1,680.00.$

is a positive number. Which is the greater quantity?

(a) 25% of one third of

(b) 33% of one fourth of

(a) is the greater quantity

CORRECT

It is impossible to determine which is greater from the information given

(b) is the greater quantity

(a) and (b) are equal

Explanation

25% of a number is the same as that number multiplied by $\frac{25}{100} = \frac{1}{4}$ , so 25% of one third of is equal to $\frac{1}{4} \cdot \frac{1}{3} Y = \frac{1}{12} Y$ .

Similarly, 33% of a number is the same as that number multiplied by $\frac{33}{100}$ , so 33% of one fourth of is equal to $\frac{33}{100} \cdot \frac{1}{4} Y = \frac{33}{400} Y$