Isabelle wants to become an astronaut! She has decided that she will spend 20% of her day studying. If she is awake for 15 hours each day, how
long is she spending studying?

3 hours

Step-by-step explanation:

Assuming that when the problem says "day" it refers to the hours of wakeness.  The problem is essentially asking to find 20% of 15.

First, convert 20% to decimal form. To do this, divide (20) by 100, this is because a percent is out of 100.

20 / 100 = 0.2

Now multiply the hours of wakeness by the percent as a decimal;

15 * 0.2 = 3

Isabelle spends 3 hours studying.

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step-by-step explanation: