Ratio With Algebraic Expression
A farmer has 45 horses and 20 cows.
(i) Write this as a ratio horses : cows. Give your answer in its simplest form. [1]
(ii) The farmer wants the ratio horses : cows to equal 5 : 3. He keeps his 45 horses but buys some more cows. Work out the number of cows he must buy. [2]
taken from Mathematics Cambridge IGCSE Test (0580 m16 qp 32)
Answer:
(i) The ratio is always expressed in the simplest form
45 : 20
Divided by 5 to become
9:4
(ii) In this case, it must be answered by algebraic expression.
Because we have not know how many cows more to be bought yet, so it is expressed by x.
The algebraic expression is become
45: (20+x)=5:3
With cross multiplication
45x3 = 5(20+x)
135 = 100 + 5x
35 = 5x 7 = x
So the number of cows he must buy are 7.
(i) Write this as a ratio horses : cows. Give your answer in its simplest form. [1]
(ii) The farmer wants the ratio horses : cows to equal 5 : 3. He keeps his 45 horses but buys some more cows. Work out the number of cows he must buy. [2]
taken from Mathematics Cambridge IGCSE Test (0580 m16 qp 32)
Answer:
(i) The ratio is always expressed in the simplest form
45 : 20
Divided by 5 to become
9:4
(ii) In this case, it must be answered by algebraic expression.
Because we have not know how many cows more to be bought yet, so it is expressed by x.
The algebraic expression is become
45: (20+x)=5:3
With cross multiplication
45x3 = 5(20+x)
135 = 100 + 5x
35 = 5x 7 = x
So the number of cows he must buy are 7.
The answer is still very confusing and I quite didn't understand the method used in (a)(ii)
ReplyDelete