There are three different hoses used to fill a pool: hose x, hose y, and hose z. hose x can fill the pool in a days, hose y in b days, and hose z in c days, where a > b > c. when all three hoses are used together to fill a pool, it takes d days to fill the pool. which of the following must be true? i. dbiii. c/3

C) I and III only

Step-by-step explanation:

Let full pool is denoted by O

Days Hose x takes to fill pool O = a

Pool filled in one day x = O/a

Days Hose y takes to fill pool O = b

Pool filled in one day y = O/b

Days Hose z takes to fill pool O = c

Pool filled in one day z = O/c

It is given that

                         a>b>c

Days if if x+y+z fill the pool together = d

1 day if x+y+z fill the pool together

I) d < c

d are days when hose x, y, z are used together where as c are days when only z is used so number of days when three hoses are used together must be less than c when only z hose is used. So d < c

III)

Using (1)

Similarly

So,

the correct answer is 1: 2

step-by-step explanation:

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