Mathematics
Grade10
Easy
Question
The time t required to empty a water tank varies inversely as the rate of pumping p. A pump can empty a water tank in 40 min. at the rate of 120 gal/min. How long it will take the pump to empty the water tank at the rate of 200
?
- 48 min
- 30 min
- 36 min
- 24 min
Hint:
Mathematical relationship between two variables which can be expressed by an equation in which the product of two variables is equal to a constant.
The correct answer is: 24 min
Here, we have to find the time required to empty tha tank.
We have, t = 
40 = 
…. k = 4800
t = 
= 
= 24 min.
Hence, the correct option is D.
Instead of taking y = k/x, we could also have taken xy = k, where k is a constant.
