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Percents and Proportions

• Percent represents a part of a whole. Remember to ask yourself if your answer makes sense. For example 50% of 120 means half of 120; 150% of 120 means over 120, in fact 120 plus an additional half.
• You can use a proportion to solve a percent problem. Set a ratio equal to an unknown out of 100.
• The number that follows the word “of” is the denominator.

Find 45% of 82.

• [x/82] = [45/100]
• 100x = 45 ×82
• 100x = 3690
• x = 3690 ÷100

• 0.60 ×29 =

Find 48% of 102.

• [48/100] = [x/102]
• 100x = 8 ×102
• 100x = 4896
• x = 4896 ÷100

What percent of 1030 is 845 to the nearest hundredth?

• [1030/845] =
• 1.2189 ×100% =

• [87/194] =
• 0.4485 ×100%

To the nearest hundredth, 10 is 45% of what number?

• [10/x] = [45/100]
• 45x = 1,000

To the nearest hundredth, 94 is 85% of what number?

• [94/x] = [85/100]
• 85x = 9,400

There are 800 students in the astronomy class at a university. This makes up 20% of the students at the school. How many students are at the university?

• [800/x] = [20/100]
• 17x = 80,000

Veronica used 75 feet of her roll of fabric. There is still 85% left of the roll. To the nearest hundredth, how long was the roll of fabric before Veronica used it?

• [75/x] = [85/100]
• 85x = 7,500

California is 163,969 square miles, which is about 4.3% the size of the United States. To the nearest square mile, how big is the United States?

• [163,696/x] = [4.3/100]
• 4.3x = 16,369,600

x = 3,806,883 square miles

*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.