problem solving 2. question 15

So this is my second problem solving set blog thing. I personally liked this problem solving set better than the last one, but I'm not sure why. I guess i just found the questions more challenging or something. I also learned that for some questions, you just have to concentrate. If you focus and think about the questions more, then you can figure them out easier. That is why I liked question 15. - at first I had no idea what to do, but then I stopped to think about it a bit, and I started understood how to do it. It was challenging, but not too challenging and forced me to really understand what the question was asking. But anyways, the question that I liked from this set was question number 15.

15. Four points are on a line segment, as shown.
If AB:BC = 1:2 and BC:CD = 8:5, then AB:BD equals?

•-----•----------•-----•
A. . . . B. . . . . . . .C. . . . D

a) 4:13
b) 1:13
c) 1:7
d) 3:13
e) 4:17

To solve this question, I first compared the second bit of information, where it says that BC:CD = 8:5, to the first part, where it says that AB:BC = 1:2. From this I figured out that if BC is equal to 8, then AB is equal 4.

1:2 = ?:8
1:2 = 4:8

I also know that CD is equal to 5. Then, in order to get BD, I added up BC and CD (8 and 5).

8 + 5 = 13

This gave me my final answer of AB:BD = 4:13 and showed that the answer is a) AB:BD = 4:13