Answer: 3/5
Step-by-step explanation:
Probabilty of blue tiles: 12/20 =3/5
Probability of letter b tiles: 10/20= 1/2
How to get the denominator?
4+6=10
2+8=10
10+10=20
The first pipe fills 1/8 of a pool in one hr.
The second pipe fills 1/4 of a pool in one hr.
(1/8+1/4)2= 3/4 done by the first two pipes in 2 hours.
Therefore the last pipe must do 1 1/4 of the filling in 2 hours, which is 5/8 per hour.
5/8x=1
x=8/5
It takes the third pipe 1 hour and 36 minutes to fill it by itself.
