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primary 5 | Maths
| Fractions
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Please solve the problem and draw the model
Date Posted: 2 years ago
Views: 598
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Since "the cost of a packet of cookies is 2/5 the cost of a packet of nuts",
we can think that one packet of cookies costs 2x, while one packet of nuts costs 5x.
Then the next statement "Nic used 2/7 of his money to buy 5 packets of cookies and 12 packets of nuts"
allows us to write this equation
5*(2x) + 12*(5x) = (2/7)*M, (1)
where M is the Nic's total money.
Simplify equation (1)
10x + 60x = (2/7)*M (2)
70x = (2/7)*M (3)
35*(2x) = (2/7)*M. (4)
From the last equation (4), you see that Nic can buy 35 packets of cookies for the same money (2/7)M
instead of 5 packets of cookies and 12 packets of nuts.
Now, regarding packets of nuts of the question (b), we can deduce from equation (3)
14*(5x) = (2/7)*M (5)
which means that for 2/7 of his money Nic can buy 14 packets of nuts.
It makes clear, that for {{{3/7}}} of his money, Nic can buy {{{(14/2)*3}}} = 7*3 = 21 packet of nuts.
we can think that one packet of cookies costs 2x, while one packet of nuts costs 5x.
Then the next statement "Nic used 2/7 of his money to buy 5 packets of cookies and 12 packets of nuts"
allows us to write this equation
5*(2x) + 12*(5x) = (2/7)*M, (1)
where M is the Nic's total money.
Simplify equation (1)
10x + 60x = (2/7)*M (2)
70x = (2/7)*M (3)
35*(2x) = (2/7)*M. (4)
From the last equation (4), you see that Nic can buy 35 packets of cookies for the same money (2/7)M
instead of 5 packets of cookies and 12 packets of nuts.
Now, regarding packets of nuts of the question (b), we can deduce from equation (3)
14*(5x) = (2/7)*M (5)
which means that for 2/7 of his money Nic can buy 14 packets of nuts.
It makes clear, that for {{{3/7}}} of his money, Nic can buy {{{(14/2)*3}}} = 7*3 = 21 packet of nuts.
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