Ratios and percents

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Mrs. Smith has 80 birds: geese, hens and ducks. The ratio of geese to hens is 1:3. 60% of the birds are ducks.

How many geese does Mrs. Smith have?

a) 16 b) 8 c) 12 d) 11


I know that if 60% if the birds are ducks, 40% are geese and hens. Now I have to find 40% of 80 so in order to do this I change 40% into a decimal, which is 0.4, and then multiply this by 80. The result of this is 32 which means there are 32 birds not including the ducks. I am sure I got this part of the question correct but after this I am not sure what to do. I started off by creating a chart because for every one geese there are three hens, so for every two geese there are six hens (multiples of three) and so on. Since this does not go evenly into 32, I know I am probably doing something wrong. I was told the answer is 8 but I do not understand why. I just know you add the 1 and the 3 and then divide this by 32 which gives you 8, but why do you do this?


I understand it now. Thanks.

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Let $G$ be the number of geese and $H$ be the number of Hens. You said $G+H=32$. And you are also given $1 \cdot H=3 \cdot G$ or $H=3G$. So $G+3G=32$ I think you can finishing solving that for $G$.

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You have computed correctly the number of hens and geese.

Now, for each goose there are three hens. If there was just one goose, the total would be $4$, but you have eight times birds as much, so there are $8$ geese and $24$ hens.