Chapter 9: Halves and Quarters

Q21Written answer

Question: 21

Shan poured 1 litre of milk into two bottles so that the first bottle holds 3/4 litre and the other holds 1/4 litre.

(a) Shade the level of milk in each bottle.

(b) How many millilitres of milk does each bottle hold?

NCERT Solutions Mathematics Class 4 Chapter 9 - 44

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Worked solution

(a) The level of milk marked is shown in the below figure:

NCERT Solutions Mathematics Class 4 Chapter 9 - 45

(b) We know 1 litre = 1000 millilitres

Quantity of milk in first bottle = 750 mL of milk

Quantity of milk in second bottle = 250 mL of milk

NCERT Book Page No: 105

Balance the Weight

NCERT Solutions Mathematics Class 4 Chapter 9 - 46

Q22Written answer

Question: 22

Choose from the weights above to make the two pans equal. In how many ways can you do it?

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Answer: There are many ways to do it. Some of the ways are as follows:

(i) 1 kg + 500 gm + 500 gm

(ii) 1 kg + 500 gm + 250 gm + 250 gm

(iii) 1 kg + 500 gm + 200 gm + 200 gm + 100 gm

(iv) 1 kg + 250 gm + 250 gm + 250 gm + 200 gm + 50 gm

(v) 1 kg + 200 gm + 200 gm + 100 gm + 500 gm

Q23Written answer

Question: 23

In how many different ways can you balance this weight of 3/4 kg?

1) ………..

2) ………..

3) …………

NCERT Solutions Mathematics Class 4 Chapter 9 - 47

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Worked solution

3/4 kg = 1000 gm × 3/4

= 750 gm

1) 250 gm + 250 gm + 250 gm

2) 250 gm + 250 gm + 200 gm + 50 gm

3) 500 gm + 250 gm

NCERT Book Page No: 106

Why is it wrong?

Q24Written answer

Question: 24

Kannan shaded some parts, as shown in the figure. But his friend Mini says that it is wrong. Explain why it is wrong.

NCERT Solutions Mathematics Class 4 Chapter 9 - 48

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Worked solution

Answer: Out of 5 parts of the rectangle, only 2 parts are coloured. Hence, it is 2/5 part which is coloured. In the triangle, we cannot say how many parts of it are coloured, but it is clear that the coloured part is less than 1/2 part. Hence, 1/2 is wrong.

Practice Time

Q25Written answer

Question: 25

There are 60 mangoes, and 1/2 of them are ripe. How many mangoes are ripe?

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Worked solution

Answer: Total number of mangoes = 60 mangoes

Hence, the number of mangoes which are ripe = 1/2 × 60

= 30 mangoes.

Therefore, 30 mangoes are ripe.

Q26Written answer

Question: 26

There are 32 children, and 1/2 of them are girls. How many children are boys?

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Worked solution

Answer: Total number of children = 32

Half of them are girls, then remaining half will be obviously boys

Hence, half of 32 = 1/2 × 32 = 16

Therefore, the number of boys is 16.

Q27Written answer

Question: 27

There are 20 stars. A quarter of them is red. How many stars are red? How many stars are not red?

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Worked solution

Answer: Total number of stars = 20 stars

1/4 stars are red

Hence, the number of red stars = 1/4 × 20

= 5 stars

Therefore, the number of stars which are red = 5 stars

Out of 20 stars, if 5 stars are red, then obviously remaining 15 stars are not red.

Therefore, the number of stars which are not red = 15 stars.

Q28Written answer

Question: 28

Ravi wants a pencil. It costs Rs. 2. He gives a one-rupee coin, one half-rupee coin and one quarter-rupee coin. Is it enough?

NCERT Solutions Mathematics Class 4 Chapter 9 - 49

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Worked solution

Answer: Total amount that Ravi gave = (1 + 0.50 + 0.25)

= Rs. 1.75

But, the cost of the pencil = Rs. 2

Money required to buy a pencil = Rs. (2.00 – 1.75)

= Rs. 0.25

Therefore, still, Rs. 0.25 is required to buy a pencil.

Hence, the money given by Ravi is not enough.

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