NCERT Solutions for Class 4 Maths - Chapter 6 - The Junk Seller

Page No 61:

Ques 1: If a person who runs a tea stall earns Rs 30 in a day, how much will he earn in 10 days? _____________
And in a month? _______________ How did you get the answer?
Ans: Earning of the man in 1 day = Rs 30 Earning of the man in 10 days = Rs 30 × 10 = Rs 300
We do it in the following manner:
1 times 30 is 30. 10 times 30 is 300.
Suppose there are 30 days in a month. Earning of the man in a month or 30 days = Rs 30×30 = Rs 900 We do it in the following manner: 3 times 30 is 90. 30 times 30 is 900.

Ques 2: Hariya and Babu want to buy a handcart for Rs 300.

Who has to pay back more — Hariya or Babu? _____________
Ans: Hariya took a loan of Rs 300 from a bank for 6 months to buy a handcart. He pays Rs 51 every month to the bank. Money paid back by Hariya to the bank in 1 month = Rs 51 Money paid back by Hariya to the bank in 6 months = Rs 51 × 6 = Rs 306
We do it in the following manner: 6 × 50 = 300 = 6 × 1 = 6 So, 300 + 6 = 306
So, Hariya paid Rs 306 to the bank after 6 months.
Babu took a loan of Rs 300 from Chunnilal for 6 months to buy a handcart. He paid Rs 360 to Chunnilal after 6 months. Thus, Babu has to pay back more than Hariya for buying the handcart.

Page No 62:

Ques 1: I have 9 rickshaws of my own. I give the rickshaws on rent. each for Rs 20 a day. On Sundays I do not take any money for them. 
In a week how much does Kiran earn from one rickshaw?
Ans: We know that there are 7 days in a week. Earning of Kiran from 1 rickshaw per day = Rs 20 Earning of Kiran from 1 rickshaw for 7 days = Rs 20 × 7 = Rs 140
We do it in the following manner: 2 times 7 is 14. 20 times 7 is 140.
Now, On Sunday, Kiran does not take any money for the rickshaws. Therefore, earning of Kiran from 1 rickshaw for 6 days = Rs 140 − Rs 20 = Rs 120 We do it in the following manner:
140-20 = 120, So, Kiran will earn Rs 120 in a week from 1 rickshaw.

Page No 63:

Ques 1: Do it mentally and write the answers.

• 2 × 6 = __________
• 20 × 6 = __________
• 2 × 60 = __________
• 3 × 42 = __________
• 4 × 80 = __________
• 4 × 81 = __________
• 9 × 25 = __________
• 31 × 9 = __________

Ans:

• 12
• 120

We do it in the following manner: 2 times 6 is 12. 20 times 6 is 120.

• 120
• 126

We do it in the following manner: 3×40 = 120
Also, 3 × 2 = 6 So, 120 + 6 = 126

• 320

We do it in the following manner: 4 times 8 is 32. 4 times 80 is 320.

• 324

We do it in the following manner: 4×80 = 320
Also, 4 × 1 = 4 So, 320 + 4 = 324

• 225

We do it in the following manner: 9×20 = 180
Also, 9 × 5 = 45 So, 180 + 45 = 225

• 279

We do it in the following manner: 30×9 = 270
Also, 1 ×9 = 9 So, 270 + 9 = 279

Ques 2: Look up the rate list to see today’s rates. Help Kiran to find out the cost of the junk.
• How much will Kiran pay for 31 kg newspaper? 1 kg newspaper costs Rs 5. 30 kg cost Rs 5 × 30 = Rs 150. So for 31 kg she pays Rs _____.
• How much will Kiran pay for 42 kg newspaper?
• Also find the cost of:
(a) 22 kg of plastic
(b) 23 kg of waste paper
(c) 12 kg of iron

Can you do this without writing? Guess the total money Kiran will pay to the junk collectors. Will it be — More than 600? — Less than 600?
Ans: 
• Cost of 1 kg newspaper = Rs 5
Cost of 31 kg newspaper = Rs 5 × 31 = Rs 155
We do it in the following manner: 5 × 30 = 150 = 5 × 1 = 5 So, 150 + 5 = 155
• Cost of 42 kg newspaper = Rs 5 × 42 = Rs 210
We do it like this: 5 × 40 = 200 = 5 × 2 = 10 So, 200 + 10 = 210
(a) Cost of 1 kg plastic = Rs 10
Cost of 22 kg plastic = 22 × Rs 10 = Rs 220
We do it in the following manner: 22 × 1 = 22 = 22 × 10 = 220
(b) Cost of 1 kg waste paper = Rs 4
Cost of 23 kg wastepaper = Rs 4 × 23 = Rs 92
We do it in the following manner: 4 × 20 = 80 = 4 × 3 = 12
So, 80 + 12 = 92(c) Cost of 1 kg iron = Rs 12
Cost of 12 kg iron = Rs 12 × 12 = Rs 144
We do it in the following manner:

Add the numbers in the box
100 + 20 + 20 + 4 = 144
Total money paid to junk collectors will be = Rs 155 + Rs 210 + Rs 220 + Rs 92 + Rs 144 = Rs 821

Page No 65:

Ques 1: Kiran bought 1 kg plastic for Rs 10, but sold 1 kg plastic for Rs 12. How much money does she earn on selling 1 kg plastic? Rs _______ So, how much money does she earn for 63 kg? Rs _______
Ans: Cost price of 1 kg plastic = Rs 10
Selling price of 1 kg plastic = Rs 12
Profit on selling 1 kg plastic = Rs (12 − 10) = Rs 2
Profit on selling 63 kg plastic = Rs 2 × 63 = Rs 126
We do it in the following manner: 2 × 60 = 120 2 × 3 = 6
120+6 = 126
Hence, Kiran will earn Rs 126 on selling 63 kg plastic.

Page No 66:

Ques 1: How much money will Dinu pay for 32 kg iron? 
Kiran buys 1 kg iron for Rs 12 but sells it for Rs 14. 
How much does she earn when she sells 32 kg iron? Rs _______
Ans: Cost of 1 kg iron = Rs 14 Cost of 32 kg iron = Rs 14 × 32 = Rs 448 We do it like this:

Add the numbers in the box
300 + 120 + 20 + 8 = 448So, Dinu will have to pay Rs 448 for 32 kg iron.
• Cost of 1 kg iron for Kiran = Rs 12
Selling price of 1 kg iron = Rs 14
Profit on selling 1 kg iron = Rs (14 − 12) = Rs 2
Profit on selling of 32 kg iron = Rs 2 × 32 = Rs 64
We do it in the following manner: 2 × 30 = 60 2 × 2 = 4
So, 60+464
Thus, Kiran earns Rs 64 on selling 32 kg iron.

Ques 2: I bought 1 kg newspaper for Rs 5, but sold it for Rs 6. How much money did I earn by selling 152 kg of newspaper? ________
Ans: Cost of 1 kg newspaper = Rs 5
Selling price of 1 kg newspaper = Rs 6
Profit on selling 1 kg newspaper = Rs (6 − 5) = Re 1
Profit on selling 152 kg newspaper = Re 1 × 152 = Rs 152
I earned Rs 152 on selling 152 kg of newspaper.

Ques 3: How much money will Dinu pay for 4 kg brass? _________ Guess the answer first.
Ans: Cost of 1 kg brass = Rs 180
Cost of 4 kg brass = Rs 4 × 180 = Rs 720
We will do it as follows:

Add the numbers in the box
400 + 320 = 720
Thus, Dinu will pay Rs 720 for 4 kg brass.

Page No 67:

Ques 1: First guess the answer and then calculate: 
(a) 37 × 18 = 
(b) 45 × 24 = 
(c) 69 × 52 = 
(d) 77 × 55 = 
(e) 142 × 5 = 
(f) 382 × 3 = 
(g) 2 × 175 = 
(h) 4 × 206 =
Ans: 
(a) 

Add the numbers in the box
300 + 240 + 70 + 56 = 666
(b)

Add the numbers in the box
800 + 100 + 160 + 20 = 1080
(c)

Add the numbers in the box
3000 + 450 + 120 + 18 = 3588
(d)

Add the numbers in the box
3500 + 350 + 350 + 35 = 4235
(e)

Add the numbers in the box
500 + 200 + 10 = 710
(f)

Add the numbers in the box
900 + 240 + 6 = 1146
(g)

Add the numbers in the box
200 + 140 + 10 = 350
(h)

Add the numbers in the box
800 + 24 = 824

Page No 68:

Ques 1: Later she paid Rs 919 to the junk collectors. When she sold the junk she got these notes and coins from Dinu.

Now you make a record in her diary. Find out how much she earned this time.

Ans: 

We do it as follows: 5 notes of 100 rupee 5 ×100 = Rs 500
1 note of 50 rupee 1 × 50 = Rs 50
18 notes of 10 rupee 18 × 1 = 18 = 18 × 10 = Rs 180
9 notes of 20 rupee 9 × 2 = 18 =9 × 20 = Rs 180
28 coins of 5 rupee 20 × 5 = 100 = 8 × 5 = 40
= 100 + 40 = 140 = 28 ×5 = Rs 140
Money I got = Rs 500 + Rs 50 + Rs 180 + Rs 180 + Rs 140 = Rs 1050
500 + 50 + 180 + 180 + 140 = 1050
Money I earned = Rs 1050 − Rs 919 = Rs 131
1050 - 919 = 131