<span>Let x=amount of time it takes both pipes draining together to empty the pool
First pipe empties at the rate of 540,000/150=3600 liters/min
Second pipe empties at the rate of 540,000/225=2400 liters/min
Together, both pipes empties at the rate of 3600+2400=6000 liters/min, so our equation to solve is:
6000*x=540000 </span>
Givens
The numbers are n and n + 1
Average = Av = 105
Equation
Av = (n)(n + 1)/2
Solution
Av = 105
n(n +1)/2 = 105 Multiply both sides by 2
n(n + 1) = 105 * 2
n(n + 1) = 210 Remove the brackets.
n^2 + n = 210 Subtract 210 from both sides
n^2 + n - 210 = 0
factor
(n+15)(n - 14)
n + 15 = 0
n = - 15
n = - 15 which is the smallest of the two answers.
n + 1 = - 14
Explanation is in the file
shorturl.at/ipxUY
Try to find the lowest common denominator. In this case it's 28, which makes our numbers as follows:
1/4 = 7/28
1/7 = 4/28
7/28 + 4/28 = 11/28
We can't simplify it so that's the result.
