Ratios, percentages, and interpreting graphs and tables
If a shirt costs $40 and is on sale for 25% off, what is the sale price?
25% of $40 is $10, so sale price = $40 - $10 = $30
The ratio of boys to girls in a class is 3:2. If there are 15 boys, how many girls are there?
3:2 ratio means for every 3 boys, 2 girls. 15 boys ÷ 3 = 5 groups, so 5 × 2 = 10 girls
If a car travels 240 miles in 4 hours, what is its average speed?
Speed = Distance ÷ Time = 240 ÷ 4 = 60 mph
What is the mean of: 12, 15, 18, 21, 24?
Mean = Sum of values ÷ Number of values = (12+15+18+21+24) ÷ 5 = 90 ÷ 5 = 18
If 30% of a number is 45, what is the number?
30% of x = 45, so x = 45 ÷ 0.30 = 150