GRADE 8 Mathematics – Rates,Ratios,Proportion and Percentages Quiz
1. What is 25% of 80?
To find 25% of a number, divide by 4. Therefore, 25% of 80 is 20.
2. If a car travels 200 kilometers in 4 hours, what is the speed of the car in kilometers per hour?
To find speed, divide distance traveled by time taken. Therefore, the speed of the car is 50 km/hr.
3. If 2 apples cost Ksh. 50, how much will 5 apples cost?
To find the cost of 5 apples, multiply the cost of 2 apples by 2.5. Therefore, 5 apples will cost Ksh. 125.
4. What is the ratio of boys to girls in a class of 30 students if there are 18 boys?
The ratio of boys to girls is 18:12, which simplifies to 3:2.
5. If a computer costs Ksh. 24,000 and this is 60% of the original price, what was the original price of the computer?
Let the original price be x. 60% of x is Ksh. 24,000. Solving for x, the original price is Ksh. 40,000.
6. If the scale on a map is 1:250,000, what would be the actual distance between two points if they are 12.5 cm apart on the map?
To find the actual distance, multiply the scale by the distance on the map. Therefore, the actual distance between the two points is 250 km.
7. If 30 is 20% of a number, what is 30% of the same number?
To find 30% of a number, multiply by 3/2. Therefore, 30% of the number is 45.
8. If 15% of a number is 9, what is 30% of the same number?
To find 30% of a number, multiply by 2. Therefore, 30% of the number is 18.
9. If it takes 8 hours for 12 workers to build a wall, how long will it take 18 workers to build the same wall?
More workers means less time needed, so the time taken by 18 workers will be less. Therefore, it will take 6 hours for 18 workers to build the wall.
10. What percentage of 120 is 36?
To find the percentage, divide the part by the whole and multiply by 100. Therefore, 36 is 30% of 120.
11. If 5 kg of sugar costs Ksh. 200, how much will 3 kg of sugar cost?
To find the cost of 3 kg of sugar, divide the cost of 5 kg by 5 and multiply by 3. Therefore, 3 kg of sugar will cost Ksh. 120.
12. Solve for x: 4 is 20% of what number?
To find the number, divide 4 by 20%. Therefore, x = 20.
13. If a recipe uses 2 cups of flour to make 12 cookies, how many cups of flour are needed to make 36 cookies?
More cookies require more flour, so the number of cups needed for 36 cookies is 6 cups.
14. If 40% of a number is 160, what is the number?
To find the number, divide 160 by 40% or multiply by 100/40. Therefore, the number is 400.
15. A car travels 300 km in 5 hours. What is the speed of the car in meters per second?
To convert km/h to m/s, multiply by 1000/3600. Therefore, the speed of the car is 20 m/s.
16. If 75% of a number is 45, what is 150% of the same number?
To find 150% of a number, multiply by 3/2. Therefore, 150% of the number is 90.
17. In a class of 40 students, the ratio of boys to girls is 3:5. How many boys are in the class?
The total parts in the ratio is 3+5=8. If there are 40 students, each part represents 40/8=5 students. Therefore, there are 3 parts of boys, which is 3*5=15 boys.
18. Solve for x: 15% of x is 30, what is x?
To find x, divide 30 by 15%. Therefore, x = 200.
19. If 4 packets of biscuits cost Ksh. 120, how much will 8 packets cost?
To find the cost of 8 packets, multiply the cost of 4 packets by 2. Therefore, 8 packets will cost Ksh. 240.
20. If the ratio of pens to pencils is 2:3 and there are 20 pencils, how many pens are there?
The ratio of pens to pencils is 2:3 which simplifies to 4:6. If there are 20 pencils, each part represents 20/6=5 pencils. Therefore, there are 2 parts of pens which is 2*5=10 pens.
21. What is 25% of 80?
To find 25% of a number, multiply the number by 0.25. So, 0.25*80 = 20.
22. If the ratio of boys to girls in a class is 2:3 and there are 25 girls, how many boys are in the class?
Since the ratio of boys to girls is 2:3, the total parts is 2+3=5. If there are 25 girls, each part represents 25/3=5 girls. Therefore, there are 2*5=10 boys. So, the total number of students is 10+25=35.
23. If a bike travels 60 km in 3 hours, what is its speed in km/h?
Speed = Distance/Time. So, 60 km / 3 hours = 20 km/h.
24. If a packet of sugar weighs 2.5 kg and costs Ksh 75, what is the cost of 1 kg of sugar?
To find the cost of 1 kg of sugar, divide the total cost by the weight. So, 75 Ksh / 2.5 kg = Ksh 30 per kg.
25. If 20% of a number is 30, what is the number?
To find the number, divide the given percentage value by the percentage. So, 30 / 0.20 = 150.
26. If a shirt costs Ksh 600 after a 20% discount, what was its original price?
Let the original price be x. After a 20% discount, the price is 80% of x. Therefore, 0.80*x = 600. Solving for x gives x = Ksh 750.
27. If a recipe calls for 2 cups of sugar to make 12 cookies, how many cups of sugar are needed to make 30 cookies?
The ratio of cups of sugar to cookies is 2:12. To find cups of sugar needed for 30 cookies, set up a proportion. So, x/30 = 2/12. Solving for x gives x = 5 cups.
28. What is 40% of 200?
To find 40% of a number, multiply the number by 0.40. So, 0.40*200 = 80.
29. If the population of a city is 500,000 and the ratio of men to women is 3:2, how many women are in the city?
Since the ratio of men to women is 3:2, the total parts is 3+2=5. If the total population is 500,000, each part represents 500,000/5=100,000 people. Therefore, there are 2*100,000=200,000 women in the city.
30. If a car travels 240 km in 4 hours, what is its speed in km/h?
Speed = distance / time. So, 240 km / 4 hours = 60 km/h.
31. If 15% of a number is 45, what is the number?
To find the number, divide the given percentage value by the percentage. So, 45 / 0.15 = 300.
32. Solve for x: 4:9 = x:18
To find x in a proportion, cross multiply. So, 4*18 = 9*x. Therefore, x = 8.
33. If a TV costs Ksh 900 after a 10% discount, what was its original price?
Let the original price be x. After a 10% discount, the price is 90% of x. Therefore, 0.90*x = 900. Solving for x gives x = Ksh 1,000.
34. If a recipe calls for 3 cups of flour to make 20 cookies, how many cups of flour are needed to make 40 cookies?
The ratio of cups of flour to cookies is 3:20. To find cups of flour needed for 40 cookies, set up a proportion. So, x/40 = 3/20. Solving for x gives x = 6 cups.
35. What is 30% of 150?
To find 30% of a number, multiply the number by 0.30. So, 0.30*150 = 45.
36. If the ratio of apples to oranges in a basket is 4:5 and there are 36 oranges, how many apples are in the basket?
Since the ratio of apples to oranges is 4:5, the total parts is 4+5=9. If there are 36 oranges, each part represents 36/5=7 oranges. Therefore, there are 4*7=28 apples. So, the total number of fruits is 28+36=64.
37. If a train travels 480 km in 8 hours, what is its speed in km/h?
Speed = distance / time. So, 480 km / 8 hours = 60 km/h.
38. If 12% of a number is 36, what is the number?
To find the number, divide the given percentage value by the percentage. So, 36 / 0.12 = 300.
39. If a laptop costs Ksh 1,200 after a 15% discount, what was its original price?
Let the original price be x. After a 15% discount, the price is 85% of x. Therefore, 0.85*x = 1,200. Solving for x gives x = Ksh 1,400.
40. If a cake recipe requires 4 cups of sugar to make 24 cupcakes, how many cups of sugar are needed to make 36 cupcakes?
The ratio of cups of sugar to cupcakes is 4:24. To find cups of sugar needed for 36 cupcakes, set up a proportion. So, x/36 = 4/24. Solving for x gives x = 6 cups.