Mastering Ratios and Proportions

If the ratio of boys to girls in a classroom is 3:4 and there are 12 boys, how many girls are there?

• 14

• 16

• 18

• 20

A recipe for a cake requires flour and sugar in the ratio 2:1. If you use 300 grams of flour, how much sugar do you need?

• 100 grams

• 150 grams

• 200 grams

• 250 grams

In a bag of red and blue marbles, the ratio of red to blue marbles is 5:3. If there are 40 blue marbles, how many red marbles are there?

• 50

• 60

• 66

• 75

A map scale is 1:100,000. If two cities are 3 cm apart on the map, how far are they apart in reality (in kilometers)?

• 3 km

• 30 km

• 300 km

• 3,000 km

The ratio of water to cement in a mixture is 7:2. If you have 14 liters of water, how many liters of cement do you need?

• 2 liters

• 4 liters

• 6 liters

• 8 liters

A group of students is planning a party. The ratio of boys to girls attending the party is 2:3. If there are 30 girls coming to the party, how many boys are coming?

• 18

• 20

• 24

• 30

A mixture contains acid and water in the ratio 1:5. How much water is there in 180 liters of this mixture?

• 30 liters

• 50 liters

• 150 liters

• 180 liters

If the ratio of the lengths of the sides of a rectangle is 3:5 and the shorter side is 9 cm long, what is the length of the longer side?

• 12 cm

• 15 cm

• 18 cm

• 21 cm

A car travels 270 kilometers using 18 liters of petrol. What is the car's fuel efficiency ratio (kilometers per liter)?

• 13 km/L

• 15 km/L

• 17 km/L

• 20 km/L

In a fruit salad, the ratio of apples to oranges to bananas is 2:3:5. If there are 10 apples, how many pieces of fruit are there in total?

• 25

• 40

• 50

• 60