Math Magic NCERT Book - Solutions
CBSE Class 5 Mathematics
NCERT Solutions
CHAPTER-1
THE FISH TALE
(1) At what price per kg did Fazila sell the king fish?
Sol (1) Price of 8kg king fish=Rs.1200
Price of 1kg king fish=Rs. (1200/8)
= Rs. 150
(2) Floramma has sold 10 kg prawns today. How much money did she get for that?
Sol. (2) Price of 1kg prawns= Rs. 150
Price of 10 kg prawns=Rs. (10
150)
=Rs. 1500
(3) Gracy sold 6 kg sword fish. Mini has earned as much money as Gracy. How many kg of sardines did Mini sell?
Sol. (3) Cost of 1 kg swordfish= Rs. 60
Gracy earned on selling 6 kg swordfish=Rs. (660) = Rs. 360
Earning of mini = Rs. 360
Cost of Sadines=Rs. 40 per kg
Quantity of sardines sold for Rs. 360= (360/40) kg= 9kg
(4) Basher has Rs.100. He spends one-fourth of the money on squid and another three-fourth on prawns.
(a) How many kilograms of squid did he buy?
(b) How many kilograms of prawns did he buy?
Sol. We have,
One-fourth of Rs.100 =Rs. (100/4) =Rs.25
Three-fourth of Rs.100= Rs. (100/4) 3 = Rs. (253) = Rs.75
(a) Cost of Squid= Rs. 50 per kg.
For Rs. 25, quantity of squid brought= half kg
[Half of Rs. 50 is Rs. 50]
(b) Cost of prawns= Rs. 150 per kg
For Rs. 75, quantity of prawns brought= half kg
[Half of Rs. 150 is Rs. 75]
Ques. Women's 'Meenkar Bank'
The meeting of the Meenkar Bank has just begun. Fazila is the president. Twenty fisherwomen have made their own bank. Each saves Rs. 25 every month and puts it in the bank.
1. How much money does the group collect each month?
2. How much money will be collected in ten years?
Sol. (1) Money collected by each member is Rs. 25 per month.
Money collected by the group of 20 members per month=Rs. (2025) =Rs. 500
(2) Money collected by the group in 10 years= Rs. (1012 500) =Rs. 60000
(a) Gracy took a loan of Rs. 4000 to buy a net. She paid back Rs. 345 every month for one year. How much money did she pay back to the bank?
Sol. (a) Loan taken by Gracy=Rs. 4000
Amount paid at the rate of Rs. 345 per month for one year= Rs. (34512) =Rs. 4140
Gracy paid back to the bank Rs. 4140
(b) Jhansi and her sister took a loan of Rs. 21000 to buy a long boat. They paid back a total of Rs. 23520 in one year. How much did they pay back every month?
Sol. (b) Amount paid back by Jhansi and her sister to the bank in one year i.e. 12months =Rs. 23250
Amount paid back every month=Rs. (23250/12) =Rs. 1960
Ques. Why Don't We Start a New Fish-drying Factory?
The women of Meenkar Bank also want to start a factory to dry fish. The Panchayat has given them some land for that. Over the years they have saved Rs 74,000. They find out how much they will need for the factory. Fazila writes the things they need to buy to begin. See the table for the cost of each item and the number of items they want to buy. Find the total cost.
Item | Price of each | No. of items | Cost |
Borewell for fresh water | Rs. 3000 | 1 |
|
Bamboo for fish drying | Rs. 2000 | 20 |
|
Cement tank | Rs. 1000 | 4 |
|
Tray and knife | Rs. 300 | 20 |
|
Bucket | Rs. 75 | 20 |
|
Total cost to set up the factory = ____________
When fresh fish is dried it becomes 
its weight. In one month they plan to dry 6000 kg of fresh fish. How much dried fish will they get in a month? ____________
Sol.
Item | Price of each | No. of items | Cost |
Borewell for fresh water | Rs. 3000 | 1 | Rs. (3000 |
Bamboo for fish drying | Rs. 2000 | 20 | Rs. (2000 |
Cement tank | Rs. 1000 | 4 | Rs. (1000 |
Tray and knife | Rs. 300 | 20 | Rs. (300 |
Bucket | Rs. 75 | 20 | Rs. (75 |
Total cost to set up the factory = Rs. 54500
Quantity of dried fish obtained in one month= of 6000 kg = (6000/3) kg= 2000 kg
Ques. Let us first calculate for 6 kg of fresh fish.
We buy fresh fish for Rs. 15 per kg
We sell dried fish for Rs. 70 per kg
We dry 6 kg fresh fish to get ………. Kg dried fish
For 6 kg fresh fish we have to pay 6………. = Rs. 90
We will sell 2 kg dried fish and get 2………. = Rs.………
So if we dry 6 kg fresh fish we will earn ………-90= Rs. ……….
But it we dry 6000 kg we can earn Rs…………1000 in one month!
Sol. We dry 6 kg fresh fish to get 2kg dried fish [6/3=2]
For 6 kg fresh fish we have to pay 6Rs. 15 =Rs. 90
We will sell 2kg dried fish and get 2 Rs. 70 =Rs. 140
So if we dry 6 kg fresh fish we will earn Rs. 140-Rs. 90= Rs. 50
But if we dry 6000 kg we can earn Rs 501000=Rs. 50000 in one month!
Ques. Jhansi- I found that for 6000 kg fish we would need 1500 kg salt every month! Its price is Rs. 2 per kg
Monthly costs:
(a) Salt 15002= Rs.………..
(b) Packing and bus charges= Rs. 3000
So the total monthly cost of drying and selling the fish =Rs. ………..
Fazila- That sounds very good! Our calculations tell us that every month our Bank will earn Rs. 44000!
1. Check to see if you also get the same answer.
Sol. Monthly costs-
(a) Salt =1500Rs. 2= Rs. 30000
(b) Packing and bus charges= Rs. 3000
So, the total monthly cost of drying and selling the fish=Rs. 3000+Rs. 3000= Rs. 6000
They earn Rs. (50000-6000) = Rs. 44000 per month
Their answer is correct.
