Atank can be filled by one pump in 50 minutes and by another pump in 60 minutes. a third pump can drain the tank in 75 minutes. if all 3 pumps go into operation, how long will it take to fill the tank? pls

9514 1404 393

  42 6/7 minutes

Step-by-step explanation:

In each minute, the first pump adds 1/50 of a tankful, the second adds 1/60, and the third subtracts 1/75. Then at the end of each minute, the amount added to the tank is ...

  1/50 +1/60 -1/75 = (6 +5 -4)/300 = 7/300 . . . tankful

The time required to fill the tank is the reciprocal of this rate:

  1/(7/300 tankful/minute) = 300/7 minutes/tankful

  300/7 minutes = 42 6/7 minutes

= 5

step-by-step explanation:

to find the 15th term substitute n = 15 into the nth term formula

= (- 3 × 15 ) + 50 = - 45 + 50 = 5