The book I'm studying from says the answer is 45.
And I'm solving it like so:
x/120 * 3/5 = 5x/360
360/5 = 72
120 - 72 = 48 ft.
Am I doing this wrong or is this an error in the book?
Thanks for reading. (and definitely helping if you can!)
ID:183331
 Aug 24 2007, 2:02 pm
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The book I'm studying from says the answer is 45. And I'm solving it like so: x/120 * 3/5 = 5x/360 360/5 = 72 120 - 72 = 48 ft. Am I doing this wrong or is this an error in the book? Thanks for reading. (and definitely helping if you can!) | |
Cheetoz wrote:
Yep, this approach is wrong. In this case x would be your AB segment, so really I have no idea where the first equation comes from. Here's the problem in simple algebraic form: AB / BC = 3 / 5 AB / (AB + BC) = 3 / 8 AB / AC = 3 / 8 AB / 120 = 3 / 8 AB = 120 * (3 / 8) = 45 Lummox JR | |
Although I don't get what you're doing in your working (you haven't even defined x), I think you don't realise that the ratio of 3:5 doesn't mean it's split like AB is 3/5s = 60% of the way along the segment. You have to add all the numbers, 3 + 5, and then each part is split like 3/(3+5) and 5(3+5). Meaning AB is 3/8 of the line segment.
So if you had the ratio 5:2:6:7, it'd be split like; 5/20, 2/20, 6/20 and 7/20. Sorry if you already realise this but you multiplying by 3/5 seemed strange. | |
15 * 3 = 45
I get the answer it does.
Now go see if you can't solve my coding problem in the code help forum!