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5 cows can eat 2 acres of grass in 10 days. How many days will it take 10 cows to eat 6 acres of grass?

Attempt at solution:

Using the given information we have:

(2 acres / 5 cows) : 10 days.

Upon multiplying both sides of the above ratio by 3/2 yields:

(6 acres / 10 cows) : 15 days.

Hence, 10 cows will eat 6 acres of grass in 15 days.

Am I correct or am on the wrong track. Please explain, as I am not very good at this easy concept.

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1 Answers 1

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I believe you are correct. My immediate reaction to any problem like this is to convert everything into common units. For these problems (numbers of items/amount/time), I often find it easiest to think about item-days.

In your example, $50$ cow-days are needed for $2$ acres. You are asked about $6$ acres so you need $150$ cow-days. With $10$ cows, that means $15$ days.