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Answer: 5/14 gallons</h3>
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Work Shown:
1/4 = 0.25
7/10 = 0.70 = 70%
We are told that 0.25 gallons of water fills 70% of the pool
We want to find how many gallons of water (call it x) are needed to fill 100% of the pool.
Set up the proportion below and solve for x
(0.25 gallons)/(70% filled) = (x gallons)/(100% filled)
0.25/70 = x/100
0.25*100 = 70x ....... cross multiply
25 = 70x
70x = 25
x = 25/70
x = (5*5)/(5*14)
x = 5/14 gallons
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An alternate method:
1/4 gallons = 7/10 pools filled
(10/7)*(1/4 gallons) = (10/7)*(7/10 pools filled)
(10*1)/(7*4) gallons = (10*7)/(7*10) pools filled
10/28 gallons = 1 pool filled
(5*2)/(14*2) gallons = 1 pool filled
5/14 gallons = 1 pool filled
In the second step, I multiplied both sides by 10/7 so that the "7/10" turns into "1".
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Yet another alternate method:
1/4 = 10/40
7/10 = 28/40
We need 10/40 gallons of water to fill 28/40 of one pool. We can multiply both fractions by 40 to indicate that 10 gallons of water will fill up 28 pools.
So we have this ratio
10 gallons : 28 pools
Dividing both parts by 28 tells us how many gallons are needed for one pool
10 gallons : 28 pools
10/28 gallons : 28/28 pools
10/28 gallons : 1 pool
5/14 gallons : 1 pool
