Percentages Study Guide Review

At the neighborhood Fourth of July party, Mrs. O’Conner plans to serve banana pudding. She plans to make 2 batches for every 9 people attending. If 72 people will attend the Fourth of July party, how many batches does Mrs. O’Conner need to make?

• 18 batches

• 16 batches

• 72 batches

• 24 batches

Answer explanation

Mrs. O’Conner needs to make 16 batches because for every 9 people attending, she plans to make 2 batches. With 72 people attending, 72 ÷ 9 = 8 groups of 9 people, so 8 groups × 2 batches = 16 batches.

Find the missing value in the proportion.

• 25.2

• 27.8

• 30.6

• 21.6

Answer explanation

To find the missing value in the proportion, we could solve it by multiplying, then dividing (28.8 * 7)/8 or dividing, then multiplying (7/8 * 28.8)

A gear rotates 8 times every 15 seconds.

Which of the statements below is NOT true?

• The gear rotates 16 times in 30 seconds.

• The gear rotates 48 times in 90 seconds.

• The gear rotates 32 times in 1 minute.

• The gear rotates 24 times in 60 seconds.

Answer explanation

The statement 'The gear rotates 24 times in 60 seconds' is NOT true because the ratio is not equivalent to "8 times in 15 seconds"

Michaela spent $234 preparing for a party with 18 guests. Each guest costs the same amount of money. How many guests could attend a party that cost $104 to prepare?

• 6 guests

• 8 guests

• 10 guests

• 12 guests

Answer explanation

To find how many guests for a $104 party, you should set up a proportion, with 18/$234 = x/ $104. You could divide 18 by $234, then multiply by $104 OR multiply 18 by $104, then divide by $234

A dolphin jumps 54 times in a 6-hour period.

At this rate, how many jumps would be expected in a 2-hour period?

• 18 jumps

• 27 jumps

• 36 jumps

• 9 jumps

Answer explanation

To find the number of jumps in a 2-hour period, divide 54 jumps by 6 hours to get the rate per hour (9 jumps). Then, multiply the rate by 2 hours to get 18 jumps expected in a 2-hour period.

A package of 12 cans of black beans cost $6.84. What is the cost of one can of black beans?

• $0.57

• $0.67

• $0.77

• $0.87

Answer explanation

To find the cost of one can of black beans, divide the total cost ($6.84) by the number of cans (12). $6.84 ÷ 12 = $0.57. Therefore, the cost of one can of black beans is $0.57.

Fifteen is 30% of what number?

• 50

• 15

• 30

• 45

Answer explanation

To find the number, set up a proportion. 15/x = 30/100. (15 * 100)/30 = 50

A recipe for lemonade punch calls for 6 cups of lemonade for every 24 cups of punch. Which of the following equations can be used to find x, the percent of lemonade in the recipe?

• 
• 
• 
• 

Answer explanation

Remember, you are looking for the percent of lemonade in the total recipe, so you will need to find the total cups in the lemonade punch (6+24). That means that the lemonade is the part and the fruit punch and lemonade together are the whole.

Of the 650 students at Westmoreland Junior High, 80% will attend the field trip. How many students will attend the field trip?

• 80 students

• 130 students

• 520 students

• 325 students

Answer explanation

To find the number of students attending the field trip, multiply 650 by 80% (0.80). 650 * 0.80 = 520 students. Therefore, 520 students will attend the field trip.

All items produced in a factory are checked for defects. Of the 300 items checked, 3% were found to be defective. How many of the items checked worked correctly?

• 9 items

• 291 items

• 100 items

• 3 items

Answer explanation

To find out how many were NOT defective, multiply the 300 items by 97% (0.97).