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Solve proportions: word problems

The Crayola crayon company can make 2400 crayons in 4 minutes. How many crayons can they make in 15 minutes?

Set up a proportion and solve for n.

$\frac{2400\;crayons}{4\;minutes}=\frac{n\;crayons}{15\;minutes}$

 4 x n = 2400 x 15 Find the cross products 4n = 36000 Multiply n = 9000 Divide both sides by 4

The Crayola crayon company can make 9000 crayons in 15 minutes.

A typist can type 120 words in 100 seconds. At that rate, how many seconds would it take her to type 258 words?

Set up a proportion and solve for n.

$\frac{120\;words}{100\;seconds}=\frac{258\;words}{n\;seconds}$

 120 x n = 258 x 100 Find the cross products 120n = 25800 Multiply n = 215 Divide both sides by 120

It would take her 215 seconds to type 258 words.