Question

There are two inlet pipes A and B.A fills the tank in 8 hours and B in 12 hours.They are opened at alternate hrs starting with A at 10 am.When will the tank be filled?

Answer 1

\[\frac{1}{8}*4+\frac{1}{10}*4 = .9\]
so its more than 4+4 = 8 hours, but:
\[\frac{1}{8}*5+\frac{1}{10}*4 = 1.025\]
so its less than 9 hours.

Answer 2

wait....im retarded

Answer 3

gotta flip those numbers

Answer 4

The options are :-
1) 21/2 2) 10 3) 19/2 4) 28/3

Answer 5

no wait...ive confused myself <.<

Answer 6

nvm, i stand by what i said in my first post lol

Answer 7

Is it c) 19/2 hrs

Answer 8

i think its 8 hrs and 48 mins.

Answer 9

it is 19/2

Answer 10

opened at alternate hours got to add it up

Answer 11

\[\frac{1}{8}+\frac{1}{12}+...=1\]

Answer 12

i guess im not seeing it correctly then? i thought that what i was doing.

Answer 13

OH, i saw a 10, but its 12 in the question.

Answer 14

i must have looked at the 10 AM part >.< bah.

Answer 15

takes 9 hours and and a little

Answer 16

oh right. nine and a half

Answer 17

how did you get that so fast? or did you do it slow?

Answer 18

tank filled at 7:30

Answer 19

it's obvious that it takes more than (5 hrs from A + 4 hrs from B) and less than (5 hrs from A + 5 hrs from B) since
5/8 + 4/12 = 0.9583
5/8 + 5/12 = 25/24 > 1
since A starts first 5 hrs of A have to be completed and (4+ ?) hrs [ say x ]of B
therefore
5/8 + x/12 = 1
=> x = 9/2
so total time = 5 hrs of A + 9/2 hrs of B
= 19/2 hrs

Answer 20

ok you actually computed but with thought. nice work