Proportion: Estimate mean length of words in book

[sky1234567]

I tried different proportions but didn't get the correct answers. I don't really understand how to set up the proportions. Is it words/letters? I tried 2/20 = x/81 but it didn't work. Please help. Thanks.

 

[ksdhart2]

Well, let's revisit the problem and see if we can't figure out what it's really asking. I suspect if you understand what the question is asking you to do, you'll be able to better determine how to solve it. The problem text says:

9. For each sample, estimate the mean length of the words in the book to the nearest tenth

I've bolded the relevant portion of the passage. That tells us what we're solving for. In this context, "mean" is the same as "average." And it asks about "length of the words." Putting that all together, we want to know how many letters an average word from each book has. You (should) know that the average number of letters can be computed by dividing the total number of letters by the number of words. Let's now step through the table and see what relevant information we can get from it about the first sample.

The first sample has one word with 1 letter. How many letters is that? There are also two words with 2 letters. How many letters is that? There's seven three-letter words, so how many letters is that? ... How many total letters are there, then, in all of the words? How many words total are there? What proportion does that suggest you might set up? If you simplify it down, how does it relate to the given answer? Now can you apply the same process to the other samples?

 

[sky1234567]

Got it! Thanks.