How to calculate the fraction and percentage of leftover pizza?
I'm helping my son with his math homework and we're stuck on a word problem. It seems simple but I want to make sure I explain it correctly.
The question is: A pizza is cut into 8 equal slices. You eat 3 of them. What percentage of the pizza is left, and what is this amount as a fraction?
I think I know the fraction, but I'm getting confused on the best way to convert that into a percentage. A step-by-step explanation would be really helpful.
3 Answers
Hi @Marco_Lombardi, you're on the right track! Here is a simple step-by-step breakdown that should help you explain it.
Step 1: Find the number of slices left. The pizza starts with 8 slices and you eat 3. So, 8 - 3 = 5 slices left.
Step 2: Write the fraction of what's left. The fraction is (Slices Left) / (Total Slices). So, the fraction is 5/8.
Step 3: Convert the fraction to a percentage. To do this, you first divide the top number by the bottom number to get a decimal. 5 ÷ 8 = 0.625 Then, you multiply the decimal by 100 to get the percentage. 0.625 x 100 = 62.5%.
So, the final answer is 5/8 of the pizza is left, which is equal to 62.5%.
A good way to double-check your work or show a different way of thinking is to calculate the percentage that was eaten first.
1. Fraction Eaten: 3 out of 8 slices = 3/8 2. Percentage Eaten: Divide 3 by 8 (3 ÷ 8 = 0.375), then multiply by 100. That's 37.5% eaten. 3. Find what's left: The whole pizza is 100%. So, 100% - 37.5% = 62.5% left.
This method gets you the same answer and can help reinforce the idea that the two parts (eaten and left) must add up to the whole (100%).
To help with the concept, you can think of a percentage as a fraction that always has 100 on the bottom.
You have the fraction 5/8.
You want to find an equivalent fraction that looks like ? / 100.
To get from 8 to 100, you have to multiply by 12.5 (since 100 ÷ 8 = 12.5).
To keep the fraction equivalent, you have to do the same thing to the top number:
5 x 12.5 = 62.5
So, 5/8 is the same as 62.5/100, which is exactly what 62.5% means!