ICSE Board: Suggested Books     ICSE Board:  Foundation Mathematics
Class 8: Reference Books               Class 8: NTSE Preparation
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Q 1. If the cost of 40 toys is 1024 Rs. what is the cost of one dozen such toys?

Answer:

Cost of 40 toys = 1024 Rs.

Therefore cost of 1 toy = (1024/40) = 25.60 Rs.

Hence the cost of one dozen toys (12 toys) = 25.60 x 12 = 307.20 Rs.

 

Q 2. If 18 notebooks cost 333 Rs. how many notebooks can be purchased for 425.50 Rs?

Answer:

Cost of 18 notebooks = 333 Rs

Cost of one notebook = (33/18) = 18.5 Rs.

Hence number of notebooks that can be purchased for 425.50 Rs = (425.50/18.5) = 23

 

Q 3. If 50 pencils can be bought for 120 Rs. how many pencils can be bought for 108 Rs.?

Answer:

50 pencils cost = 120 Rs.

Cost of one pencil = (120/50) = 2.4 Rs.

Hence the number of pencils that can be bought for 108 Rs. = (108/2.4) = 45 pencils

 

Q 4. If 45 iron rods of the same size weigh 12.6 kg, how much is the weight of 24 such rods?

Answer:

Weight of 45 rods = 12.6 kg

Weight of one rod = (12.6/45) = 0.28 kg

Weight of 24 such rods = 0.28 x 24 = 6.72 kg

 

Q 5. If a laborer earns 784 Rs. per week, how much will he earn in 15 days?

Answer:

Weekly salary of the labor = 784 Rs.84/7) = 112 Rs.

Earning for 15 days = 15 x 1

Daily Salary of the labor = (712 = 1680 Rs

 

Q 6. If a car covers 56.7 km in 4.5 liters of petrol, how many kilometers will it cover in 26 liters of petrol?

Answer:

In 4.5 liters of petrol the car covers = 56.7 km

In one liter of petrol the car will cover = (56.7/4.5) = 12.6 km

In 26 liters of petrol, the car will cover = 12.6 x 26 = 327.6 km

 

Q 7. 15 men can do a piece of work in 36 hours. How many men will be required to finish the work in 20 hours?

Answer:

15 men can do a piece of work in 36 hours

Total man hours required for finishing the job = 15 x 36 = 540 man hours

To finish the work in 20 hours we would need =540/20 = 27 men

 

Q 8. 13 men can weave 117 baskets in a week. How many men will be needed to weave 189 baskets in 3 days?

Answer:

117 baskets are produced in = 13 x 7 = 91 man days

To produce one basket = (117/91) = 9/7 man days

The no. of men required to produce 189 baskets in 3 days = (7 x 189)/ (3 x 9) = 49 men

 

Q 9. A journey by car takes 48 minutes at 65 km/hr. How fast must the car go to finish the journey in 40 minutes?

Answer:

Distance covered by the car in 48 minutes = 65 x (48/60) = 52 km

Speed at which the car must go to finish the journey in 40 minutes = (52 x 60/40) = 78 km/hr.

 

Q 10. In a zoo, 28 parrots consume 7420 g of nuts in a day. If 8 parrots are sent to another zoo, what quantity of nuts will be required in a day?

Answer:

28 parrots consume = 7420 gm of nuts

1 parrot will consume = (7420/28) = 265 gm of nuts

Hence 20 parrots will consume = 265 x 20 = 5300 g of nuts per day

 

Q 11. If 5 men or 7 women can earn 700 Rs. per day, how much would 7 men and 11 women earn per day?

Answer:

5 men earn = 700 Rs. Per day

Hence, 1 man would earn = (700/5) = 140 Rs. Per day

Similarly, 1 woman would earn = (700/7) = 100 Rs. Per day

Therefore 7 men and 11 women would earn = 7 x 140 + 11 x 100 = 2080 Rs. Per day.

 

Q 12. If 5 laborers earn 9000 in 15 days, how many laborers can earn 6720 in 8 days?

Answer:

5 laborers in 15 days earn = 9000 Rs.

75 labor days = 9000 Rs.

1 Labor Day = (9000/75) = 120 Rs. Per day

Hence the number of laborers days required to earn 6720 Rs in 8 days = (6720/120) = 56

Therefore the number of laborer required = 56/8 = 7 laborers

 

Q 13. A fort had provisions for 450 men for 80 days. After 10 days, 50 more men arrived. How long will the remaining food last at the same rate?

Answer:

Provision = 450 x 80 = 36000 man days

Food consumed by 450 men in 10 day = 450 x 10 = 4500 man days

Provisions left = 36000 – 4500 = 31500 man days

After 10 days, the number of men = 450 + 50 = 500

Therefore the number of days the provision would last = 31500/500 = 63 days

 

Q 14. 3 typists working 7 hours a day, type a thesis in 10 days. For how many hours per day should 2 typists work to finish it in 21 days?

Answer:

Total work to be done = 3 x 7 x 10 = 210 man hours

So the number of hours per day by for 2 typists in 21 days = (210/42) = 5 hours per day

 

Q 15. 7 workers working 6 hours a day can build a wall in 12 days. How many days will 3 workers take to build a similar wall, working 8 hours a day?

Answer:

Total man hours to build a wall = 7 x 6 x 12 = 504 man hours

Number of days 3 workers working 8 hours a day to complete the wall = 504/(3 x 8) = 21 days

 

ICSE Board: Suggested Books     ICSE Board:  Foundation Mathematics
Class 8: Reference Books               Class 8: NTSE Preparation
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