Question

Luna observed that in the last 12 issues, 384 of the 960 pages contained an advertisement. If there are 80 pages in this weeks edition, how many pages can she predict will have advertisements?

Answer 1

I would say `32`

Explanation:

Each issue contains:
`960/12=80` pages (as suggested in the problem);
and:
`384/12=32` pages of ads for each issue.
We can suppose that also in this week edition the pattern will repeat.

Answer 2

A slightly different presentation of method

Explanation:

over a total of 12 issues a count yielded 384 adverts over a total of 960 pages.

As this was observed over a number of issues we can use these counts to derive a mean count of adverts per page.

So as a mean value there is `384-:960 =384/960` adverts per page.

Thus for a 80 page issue an `ul("'estimate'")` of the expected count of adverts is:

`384/960xx80 = 32`
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A mean value is a bit like smoothing out a 'spiky' graph. So it is a single value representation of values that are spread over a range. Thus the use of a mean in further calculations does not guarantee the final derived answer. It is more likely that what you seek lies within a range of values.

Answer 3

`32` pages

Explanation:

We can consider the information as a comparison between the number of pages of adverts and the total number of pages.

This represents a DIRECT PROPORTION

The more pages in total, the more pages of adverts.

We can show this as an equivalent fraction:

`384/960 = x/80" "(larr"number of advert pages")/(larr"total number of pages")`

We can calculate `x` from:

`(384 div 12)/(960div12) = 32/80`

Or by cross-multiplying:

`x = (384 xx 80)/960 = 32`