Easy Algebra

[christinaeconrad]

I know this is supposed to be an easy question but for some reason I'm having a really hard time grasping the answer. Is there a way you can explain it differently than the book does?

Question #10 on pg. 154 in guide #1:
At graduation, guests sit in rows such that there are p people in the first row, p+1 people in the second row, p+2 people in the third row and so on. How many more people sit in row n than in the second row?

Answer is n-2 but I'm still having a hard time getting there.

[tommywallach]

Hey Christina,

I don't know how the book explains it, but it's such a weird question that I think the only logical way to do it is just to use real numbers and try to figure it out that way.

Just invent values. Let's say p=4, so 4 people sit in the first row, 5 in the next row, etc.

Now let's pick a value for n. Let's say it's 8. How many people are in the 8th row? Well, we know that 4 people were in the first row, 5 in the second, 6 in the third, 7 in the fourth, 8 in the fifth, 9 in the sixth, 10 in the seventh, and 11 in the eighth. So there are 11 people in row n and 5 in the second row. So that's 6 more people, which in this case is p+2 (because our p was 4). That's the only way I would ever do this.

-t

[dmwojo83]

I also am having a difficult time figuring out this easy question; the way you solved it above makes sense, however how are you able to figure out the book answer of n-2, or is this a misprint?

[dmwojo83]

Thanks!

[tommywallach]

Wait...did you come to understand it? Once you have the values as I described them, you just plug into the answer choices until the correct one fits.

-t