Brain Teasers

[ddefina]

A contractor estimated that one of her two bricklayers would take 9 hours to build a certain wall and the other 10 hours. However, she knew from experience that when they worked together, 10 fewer bricks were laid per hour. Since she was in a hurry, she put both workers on the job and found it took exactly 5 hours to build the wall. How many bricks did the wall contain?

 

[rtstrading]

sure are good at picking socks, but what about stocks?

 

[Rigel]

190

 

[jaan]

X = number of bricks in the wall
speed1 = X/9 bricks per hour
speed2 = X/10 bricks per hour
overhead = 10 bricks per hour
speed3 = speed1 + speed2 - overhead = (X/9 + X/10 - 10) bricks per hour
speed3 = X/5 bricks per hour

X/9 + X/10 - 10 = X/5
X/9 + X/10 - X/5 = 10
10X + 9X - 18X = 900

X = 900

- jaan

 

[Te']

Quote from ddefina:

Test your IQ:

http://www.highiqsociety.org/noflash/nonmembers/iqtests.htm?IQ

Are these accurate???

 

[Runningbear]

No the answer is two - assuming the first two socks are red!

Runningbear

 

[daniel_m]

Quote from Te':



Are these accurate???

i'm getting results similar to what i normally get, so i guess they are.

 

[ddefina]

Quote from jaan:

X = number of bricks in the wall
speed1 = X/9 bricks per hour
speed2 = X/10 bricks per hour
overhead = 10 bricks per hour
speed3 = speed1 + speed2 - overhead = (X/9 + X/10 - 10) bricks per hour
speed3 = X/5 bricks per hour

X/9 + X/10 - 10 = X/5
X/9 + X/10 - X/5 = 10
10X + 9X - 18X = 900

X = 900

- jaan

Correct.

 

[Te']

Quote from daniel_m:



i'm getting results similar to what i normally get, so i guess they are.

I don't know Danny Boy I am definately not that bright; although I have never actually taken one of these tests before...

 

[ddefina]

For reference, I believe a dog has an IQ of 60.