PSAT Math : How to find percentage equivalent to a decimal

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1 : How To Find Percentage Equivalent To A Decimal

If 20% of x is equal to 160% of y, then y is what percent of x?

Possible Answers:

8

12.5

800

125

1.25

Correct answer:

12.5

Explanation:

We are told that 20% of x is equal to 160% of y. We need to write expressions for 20% of x and 160% of y and set them equal to one another.

In order to find an expression for 20% of x, we can write 20% as a decimal and multiply it by x. Since 20% = 0.20, we can write 20% of x as 0.2x.

Similarly, we can write 160% as 1.60y.

Now, we set these expressions equal to one another.

0.2x = 1.60y.

Since the question asks us to find y as a percentage of x, we need to solve for y in terms of x. Let's divide both sides of the equation by 1.60.

0.125x = y.

Therfore, y is equal to 0.125x, which is the same as 12.5% of x, since 12.5% expressed as a decimal is 0.125.

The answer is 12.5. 

Example Question #61 : Percentage

Express .789 as a percentage.

Possible Answers:

7.89%

78.9%

789%

0.789%

Correct answer:

78.9%

Explanation:

Move the decimal two places to the left to convert a decimal to a percentage. Therefore, .789 is equivalent to 78.9%.

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