Here’s a fun little math story problem that challenged my math skills–something that happens far too little these days. I got it from a friend’s Xanga. The answer is below the fold. But try to figure out the answer (without looking!) and post the step by step solution as a comment.
A man can paint a house in 5 days. He and his brother can paint the same house in just 3 days. How long would it take his brother to paint the house by himself?
Because it takes the man 5 days to paint the house, it means that he paints at a speed of 1/5 house per day. So working together, obviously the man paints 3/5 of the house over the 3 days he and his brother work together. His brother obviously does the rest, which is 2/5 of the house. So his brother does 2/5 of the house in 3 days. The brother thus has a speed of 2/15 (2/5 divided by 3) of a house per day. (For comparison, the first man’s speed is 1/5 or 3/15.) So the brother would require 7.5 days (15 divided by 2) to paint the house by himself.
That’s what I think the answer is, but I could have messed up. Let me know if I did.
2 Responses
May 15th, 2008 at 3:35 am
1/5 + 1/x = 1/3
LCM is 15x, thus the equation:
3x + 15 = 5x
15 = 2x
7.5 = x
I knew that Algebra was good for something
May 26th, 2008 at 9:17 am
Hans
What fantastic photos on your site of fishing in Fujairah.
Do you mind if I post one or two of your photos on my Fujairah in Focus site with a link to yours?
When did you take these pics? Do you live in Fujairah or elsewhere?
Geoff
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