Answer:
(A) 5/11
Explanation:
in 1 minute the hot faucet fills 1/12 of the bathtub.
in 1 minute the child faucet fills 1/10 of the bathtub.
so, together they have filled
1/12 + 1/10 of the bathtub.
1/12 + 1/10 = 5/60 + 6/60 = 11/60 of the bathtub.
that means out of the 5+6 = 11 parts of water in the bathtub 5 parts came from the hot faucet.
so the fraction of hot faucet water in the bathtub is 5/11 (while 6/11 came from the cold faucet).
and for the rest of the time until the bathtub is fully filled, the ratio between hot and cold water will stay the same.
therefore, also at a full bathtub, the fraction of hot faucet water is 5/11.
and answer A is correct.
FYI : it will take x minutes to fill the whole bathtub.
the whole is 1 or 60/60.
x×11/60 = 1
x = 60/11 = 5.454545454... minutes = 5 5/11 minutes =
= 5 minutes 27.272727... seconds =
= 5 minutes 27 3/11 seconds