**Unitary Method**

**Question 1:**The cost of 6 notebooks is Rs 300. Find:

**Solution:**It is given that the cost of 6 notebooks = Rs 300. Hence the cost of 1 notebook = Rs 50. Now,

**Question 2:**2 balls cost Rs 8. Find the cost of 3 balls.

**Solution:**Cost of 2 balls = Rs 18

**Question 3:**Cost of 1 book is Rs 120. What is the cost of 10 such books?

**Solution:**Cost of 1 book = Rs 120

Cost of 10 books = Rs 120 × 10

= Rs 1200

**Question 4:**12 oranges cost Rs 60. Find the cost of 6 oranges.

**Solution:**Cost of 12 oranges = Rs 60

**Question 5:**Cost of 5 pens is Rs 50. What is the cost of 1 pen?

**Solution:**Cost of 5 pens = Rs 50

Cost of 1 pen = Rs 50 ÷ 5

= Rs 10

**Question 6:**6 pencils cost Rs 96. How much will 2 such pencils cost?

**Solution:**Cost of 6 pencils = Rs 96

**Question 7:**Cost of 10 note books is Rs 250. Find the cost of 15 note books.

**Solution:**Cost of 10 note books = Rs 250

Cost of 1 note book = Rs 250 ÷ 10

= Rs 25

Cost of 15 note books = Rs 25 × 15

= Rs 375

**Question 8:**Cost of 5 chocolates is Rs 35. Find the cost of 10 chocolates.

**Solution:**Cost of 5 chocolates= Rs 35

Cost of 1 chocolate = Rs 35 ÷ 5

= Rs 7

Cost of 10 chocolates = Rs 7 × 10

= Rs 70

**Question ****9:** If the cost of 5 pens is Rs 50,
then find the cost of 8 pens.

**Solution:** Cost of 5 pens = Rs 50

[Here, 5 is the total units and Rs 50 is the total value]

Cost of 1 pen = Rs 50/5 = Rs 10 [Value of 1 unit is Rs 10]

Therefore, cost of 8 pens = Rs 10 × 8 = Rs 80

[Multiplying
the value of 1 unit with the required number of units]

**Question ****10:** 40 people can sit in four
cabs. How many people can sit in 19 such cabs?

**Solution: **Number of people who can sit in 4 cabs = 40 people

Number of people who can sit in 1 cab = 40 4 people = 10 people

Therefore, number of people who can sit in 19
cabs = 10 × 19 = 190 people

**Question 11: **If
a bus consumes 9 litres of petrol to cover 162 km, find how many litres of
petrol are required to cover 306 km.

**Solution: **For
162 km, petrol needed = 9 litres

For 1 km, petrol needed = 9/162
litres

For 306 km, petrol needed = 9/162
× 306 = 17 litres.

Hence, 17 litres of petrol are
required to cover 306 km.

**Question 12: **The
price of 52 kg of wheat is Rs 468. Find the price of 3 quintals of wheat.

**Solution: **Price
of 52 kg of wheat = Rs 468

Price of 1 kg of wheat = Rs 468/52

Price of 3 quintals, i.e. 300 kg
of wheat = Rs 468/52 × 300 = Rs 2700

Hence, the price of 3 quintals of wheat is Rs 2700.

**Question 13: **An
army camp of 200 men has enough food for 60 days. How long will the food last
if the number of men in the camp increases to 240?

**Solution: **More
men, less days and less men, more days.

It is a case of inverse variation.

According to the question, since
200 men have enough food for 60 days.

1 man will have enough food for 60
× 200 days.

240 men will get food for 60 × 200/240
days = 50 days

Hence, 240
men will get food for 50 days.

**Question 14:** Heena can type 30 words per
minute. How many minutes does she take to type 150 words?

**Solution: **Heena** **can type** **30 words in 1 min.

She can type 1 word in 1/30 min.

She can type 150 words = 1/30 × 150 = 5 min

**Question 15: **A factory produces 480 cans in 12 minutes. At this rate, how many cans
does it produce in 1 hour?

**Solution: **13 min → 520 cans

1 min → 480 ÷ 12 = 40 cans

60 min → 40 × 60 = 2400 cans

The company produces 2400 cans in 1 hour.

**Questions and Answers on
Unitary Method**

**Question 1:** If the cost of 4 kg of apples is Rs 480, then
what will be the cost of 15 kg of apples?

**Answer:** Rs 1800

**Question 2:** A car can travel 150 km in 3 hours. How much
distance can it travel in 12 hours?

**Answer:** 600 km

**Question 3:** If 5 packets can hold 45 candies, then how many
candies are there in 9 such packets?

**Answer:** 81 candies

**Question 4:** The cost of 6 notebooks is Rs 300. What will be
the cost of 14 such notebooks?

**Answer:** Rs 700

**Question 5:** 7 cartons can hold 84 oranges. How many oranges
can 11 cartons hold?

**Answer:** 132 oranges

**Question 6:** The cost of 10 books is Rs 1200. What will be
the cost of 16 such books?

**Answer: **Rs 1920

**Question 7:** One dozen eggs cost Rs 48. Find the cost of 8 eggs.

**Answer: **Rs 32

**Question 8:** The price of 12 kg of rice is Rs 360. What is
the cost of 23 kg of rice?

**Answer:** Rs 690

**Question 9:** An airplane journey of 400 km costs Rs 4400. How much will a journey
of 600 km cost?

**Answer: **Rs 6600

**Question 10:** A bus covers 240 km in 6 hours. How many
kilometres will it cover in 14 hours?

**Answer: **560 km

**Note:**

1. If the cost of one
object is given, we can find the cost of many objects by multiplying the cost
of one object with the number of objects.

2. If the cost of several
objects are given, we can find the cost of one object by dividing the cost of
several objects by the number of objects.