self Maths Puzzle

A water tank can be filled by pipe P alone in 30 minutes and by pipe Q alone in 40 minutes. The same tank can be emptied by pipe R in 25 minutes. If all the three pipes are opened at the same time, how long will it take to fill the water tank?
a) 90 min
b) 150 min
c) 120 min
d) 60 min
e) None of these

Read Solution (Total 2)

e) None of these

Tank will be filled in
1/(1/30 +1/40 -1/25) = 600/11 minutes
12 years agoHelpfull: Yes(4) No(2)

1/30+1/40-1/25=11/600==none of these
12 years agoHelpfull: Yes(0) No(3)

self Other Question

From 3 men and 4 women, three persons are to be selected in such a way that at least one women is selected. In how many different ways can they be selected?
a) 60
b) 42
c) 21
d) 36
e) None of these The sum of a number and the number preceding it is 33. By how much is two less than six times the
number?
a) 196 b) 94 c) 90 d) 100