Bluebook SAT Test Percentages Ratios and Proportions 1 — Questions and Answers
Question 1: A shirt originally costs $40 and is on sale for 25% off. What is the sale price?
- $10
- $25
- $30 (Correct answer)
- $35
Correct answer: $30
Discount = 25% × $40 = $10. Sale price = $40 − $10 = $30.
A 25% discount on $40 means the discount amount = 0.25 × $40 = $10. The sale price = $40 − $10 = $30. Alternatively, the sale price = 75% of $40 = 0.75 × $40 = $30.
Question 2: A car travels 240 miles in 4 hours. At the same rate, how many miles will it travel in 7 hours?
- 360
- 400
- 420 (Correct answer)
- 480
Correct answer: 420
Rate = 240/4 = 60 mph. Distance in 7 hours = 60 × 7 = 420 miles.
The rate is 240 miles ÷ 4 hours = 60 miles per hour. At this rate, in 7 hours the car travels 60 × 7 = 420 miles. You can also use the proportion: 240/4 = x/7, giving x = 420.
Question 3: The ratio of boys to girls in a class is 3:5. If there are 24 boys, how many girls are there?
- 32
- 36
- 40 (Correct answer)
- 45
Correct answer: 40
3/5 = 24/x → x = 24 × 5/3 = 40.
The ratio boys:girls = 3:5. With 24 boys: 3/5 = 24/x. Cross-multiply: 3x = 120, so x = 40 girls. Alternatively, each 'part' = 24/3 = 8, so girls = 5 × 8 = 40.
Question 4: A population increased from 4,000 to 5,200. What is the percent increase?
- 20%
- 25%
- 30% (Correct answer)
- 35%
Correct answer: 30%
Percent increase = (change/original) × 100 = (1200/4000) × 100 = 30%.
The change in population is 5,200 − 4,000 = 1,200. Percent increase = (1,200/4,000) × 100% = 0.30 × 100% = 30%.
Question 5: If 3 apples cost $1.50, how much do 10 apples cost?
- $3.50
- $4.00
- $5.00 (Correct answer)
- $4.50
Correct answer: $5.00
Cost per apple = $1.50/3 = $0.50. 10 apples = 10 × $0.50 = $5.00.
The unit cost per apple = $1.50 ÷ 3 = $0.50 per apple. For 10 apples: 10 × $0.50 = $5.00. You can also use the proportion: 1.50/3 = x/10, giving x = $5.00.
Question 6: What is 35% of 280?
- 84
- 91
- 98 (Correct answer)
- 105
Correct answer: 98
35% × 280 = 0.35 × 280 = 98.
To find 35% of 280: 0.35 × 280 = 98. You can also break it down: 10% of 280 = 28, so 35% = 3.5 × 28 = 98.
Question 7: A recipe calls for 2 cups of flour for every 3 cups of sugar. If you use 9 cups of sugar, how many cups of flour are needed?
- 4
- 5
- 6 (Correct answer)
- 7
Correct answer: 6
Ratio 2:3 = x:9. x = 2 × 9/3 = 6.
The ratio of flour to sugar is 2:3. If sugar = 9 cups, set up the proportion: 2/3 = x/9. Cross-multiplying: 3x = 18, so x = 6 cups of flour.
Question 8: A price dropped from $80 to $60. What is the percent decrease?
- 20%
- 25% (Correct answer)
- 30%
- 33%
Correct answer: 25%
Percent decrease = (20/80) × 100 = 25%.
The decrease is $80 − $60 = $20. Percent decrease = ($20/$80) × 100% = 0.25 × 100% = 25%. Note: the decrease is always divided by the original (not new) price.
Bluebook SAT Test Percentages Ratios and Proportions 1
A shirt originally costs $40 and is on sale for 25% off.
What is the sale price?