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  1. math_celebrity

    There are 60 students in a class. Three-fourths of them are girls. How many boys are there

    There are 60 students in a class. Three-fourths of them are girls. How many boys are there In the class, we have either boys or girls. Total students = 60 3/4 of 60 = 60 * 3/4 Since 60/4 = 15, we have: 15 * 3 = 45 girls Boys = 60 - girls Boys = 60 - 45 Boys = 15
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    After 20 minutes, Juan had completed 12 questions, which is 0.7 of his assignment. What percent of t

    After 20 minutes, Juan had completed 12 questions, which is 0.7 of his assignment. What percent of the assignment has Juan NOT completed? We know that 0.7 as a percentage is: 0.7 * 100% = 70% In this problem, we have either or. Juan either completed the question or DID NOT complete the...
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    There is a sales tax of $15 on an item that costs $153 before tax. A second item costs $81.60 before

    There is a sales tax of $15 on an item that costs $153 before tax. A second item costs $81.60 before tax. What is the sales tax on the second item? We assume the goods are bought in the same store, so tax rates are the same: Tax Rate = Tax Amount / Cost before tax Tax Rate = 15/153 Tax Rate =...
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    Jerry, an electrician, worked 7 months out the year. What percent of the year did he work?

    Jerry, an electrician, worked 7 months out the year. What percent of the year did he work? We know that there are 12 months in a year. Percentage worked = Months worked in a year / months in a year * 100% Percentage worked = 7/12 * 100% Percentage worked = 0.5833333 * 100% Multiplying by 100...
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    Suppose 5% of a package of balloons are yellow balloons. Then what percentage of balloons are a diff

    Suppose 5% of a package of balloons are yellow balloons. Then what percentage of balloons are a different color than yellow? Our total possibilities of any color balloon is 100%. So we have: Non-yellow balloons = 100% - yellow balloons percent Non-yellow balloons = 100% - 5% Non-yellow balloons...
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    Heather has completed six deliveries so far this week she needs to make 40 deliveries for the week w

    Heather has completed six deliveries so far this week she needs to make 40 deliveries for the week what percentage of her deliveries has Heather completed? We want 6/40 as a percent which is 15%
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    The astronomer found that 0.017 at the stars examined were red dwarfs. if 29,000 stars or examined,

    The astronomer found that 0.017 at the stars examined were red dwarfs. if 29,000 stars or examined, how many were not red dwarfs? If 0.017 were red dwarfs, then we have a not red dwarfs percent of: Not red dwarfs pct = 1 - red dwarfs Not red dwarfs pct = 1 - 0.017 Not red dwarfs pct = 0.983...
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    Because of the promotion, attendance exceeded normal by 275 percent. If the normal attendance was 66

    Because of the promotion, attendance exceeded normal by 275 percent. If the normal attendance was 6600 people, how many people attended? Find the exceeded multiplier: Exceeded Multiplier = Exceed percent / 100 275% as a decimal = 2.75 We multiply as follows: Exceeded Attendance = Normal...
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    A teacher’s salary was $3300 after she had received an increase of 10%. Calculate the teacher’s sala

    A teacher’s salary was $3300 after she had received an increase of 10%. Calculate the teacher’s salary if she has received an increase of 20% instead. First, we need to find the starting salary. Let the starting salary be s. Since 10% as a decimal is 0.10, We're given: s*(1.10) = 3300 1.10s =...
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    A store is offering a 15% discount on all items. Write an equation relating the sale price S for an

    A store is offering a 15% discount on all items. Write an equation relating the sale price S for an item to its list price L If we give a discount of 15%, then we pay 100% - 15% = 85% of the list price. 85% as a decimal is 0.85, So we have: L = 0.85S
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    About 3/5th of the registered voters participated in 2016 election. California has 25 million regist

    About 3/5th of the registered voters participated in 2016 election. California has 25 million registered voters. Find the number of registered voters who participated in 2016 election. 3/5 of 25000000 = 15,000,000
  12. math_celebrity

    There are 24 students in a class. Three new students joined the class. Work out the percentage chang

    There are 24 students in a class. Three new students joined the class. Work out the percentage change in the number of students in the class. We want to know how much an increase of 3 people is in a class of 24: 3/24 Using our percentage/decimal calculator, we get: 12.5% increase
  13. math_celebrity

    A man bought a mobile phone for $800 and sold it for $1000. What was his profit as a percentage of t

    A man bought a mobile phone for $800 and sold it for $1000. What was his profit as a percentage of the cost price Calculate Profit: Profit = Sales Price - Cost Profit = 1000 - 800 Profit = 200 Calculate profit percentage: Profit Percentage = Profit * 100 / Cost Profit Percentage = 800 * 100 /...
  14. math_celebrity

    The sales tax rate in a city is 7.27%. How much sales tax is charged on a purchase of 5 headphones

    The sales tax rate in a city is 7.27%. How much sales tax is charged on a purchase of 5 headphones at $47.44 each? What is the total price? First, calculate the pre-tax price: Pre-tax price = Price per headphone * Number of Headphones Pre-tax price = $47.44 * 5 Pre-tax price = $237.20 Now...
  15. math_celebrity

    Kim read 95% of a book. What percent of the book was not yet read?

    Kim read 95% of a book. What percent of the book was not yet read? The full book is 100%. So percent unread is: Percent Unread = 100% - Percent Read Percent Unread = 100% - 95% Percent Unread = 5%
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    A woman whose income for the year was $42,800 paid $10,700 in taxes. What percent of her income did

    A woman whose income for the year was $42,800 paid $10,700 in taxes. What percent of her income did she pay in taxes? Tax Percent = Tax Amount / Income * 100% Tax Percent = $10,700 / $42,800 * 100% Tax Percent = 0.25 * 100% Tax Percent = 25%
  17. math_celebrity

    41% of the passengers on the plane are men. 36% of them are women and 11% of them are boys. The rema

    41% of the passengers on the plane are men. 36% of them are women and 11% of them are boys. The remaining 30 passengers are girls. How many passengers are on the plane? Add up the percents: 41% + 36% + 11% = 88% This means that (100% - 88% = 12%) are girls. So if the total amount of...
  18. math_celebrity

    In one day, a store sells 14 pairs of jeans. The 14 jeans represent 20% of the total number of items

    In one day, a store sells 14 pairs of jeans. The 14 jeans represent 20% of the total number of items sold that day. How many items did the store sell in one day? Explain or show how you got your answer. 14 = 20%s where s is the number of items sold in one day. We can write 20% as 0.2, so we...
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    Rose weighs 140 pounds and gains 10%. What percent of her new weight must she lose to get back to 14

    Rose weighs 140 pounds and gains 10%. What percent of her new weight must she lose to get back to 140 pounds? Find her new weight after the 10% gain: New Weight = Starting Weight * (1 + 10%) Since 10% is 0.1, we have: New Weight = Starting Weight * (1 + 0.1) New Weight = Starting Weight *...
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    A laundry basket contains 30 socks, of which 9 are black. What is the probability that a randomly s

    A laundry basket contains 30 socks, of which 9 are black. What is the probability that a randomly selected sock will be black? P(Black) = 9/30 Simplifying, we can divide top and bottom by 3: 3/10 3/10 as a percentage is 30%
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