Question

It takes craig 5 minutes to type t pages. At this rate, how many minutes will it take him to type 20 pages?

Answer 1

5t = minutes to type t pages

t is the amount of pages that are going to be written, so in this case, t = 20

so instead of 5t, you would write 5(20)

5(20) = 100

100 minutes to write 20 pages

Answer 2

(100/t) minutes

Explanation:

Craig's rate can be written as (5 minutes/t pages). This is a conversion factor. This means we can also invert the factor to (t pages/5 minutes), if desired. A conversion factor tells us the that top value is equal to the bottom value, such as 12 inches/1 foot. This can be inverted to 1 foot/12 inches.

We want to know how many minutes Craig needs to type 20 pages. Assuming no distractions, we can use the conversion factor.

We can write: (20 pages)*(5 minutes/t pages)

(20 pages)*(5 minutes/t pages)

(20 )*(5 minutes/t ) [The pages unit cancels]

(100/t) minutes

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We don't know the value of t, so the result must include t. If t happens to be 2 pages, for example, it would take Craig (100/2) or 50 minutes, to type 20 pages.