Four pipes can fill a tank in 70 minutes.how long will it takes to fill the tank if 7 pipes are used.
7/4 as many pipes, so 4/7 as long: 40 minutes
To find out how long it will take to fill the tank with 7 pipes, we need to determine the rate at which one pipe fills the tank and then scale up to the rate at which 7 pipes fill the tank.
Given that 4 pipes can fill the tank in 70 minutes, we know that the combined rate of these 4 pipes is equal to 1 tank per 70 minutes.
Now, we need to find the rate of one pipe. Since there are 4 pipes, the rate of one pipe is 1/4th of the combined rate of the 4 pipes. Thus, the rate of one pipe is 1 tank per (70 minutes * 4) = 1/280th of the tank per minute.
To determine the rate at which 7 pipes fill the tank, we multiply the rate of one pipe by 7. Therefore, the rate of 7 pipes will be 7 * (1/280) tanks per minute = 7/280 tanks per minute.
Now, we can determine how long it will take to fill the tank with 7 pipes. Since the rate is given in tanks per minute, we can use the reciprocal of the rate (time per tank).
The time it takes to fill the tank with 7 pipes is 1 / (7/280) = 280/7 = 40 minutes.
Therefore, it will take 40 minutes to fill the tank if 7 pipes are used.