Let Party A work alone for 6 days, and then Party B will work alone for 9 days to complete the task, which means that Party A and Party B cooperate for 6 days and Party B will work alone for 3 days.
3/[ 1-(6/8)]
=3/( 1/4)
= 12
It takes 12 days for Party B to complete this project alone.
Xiaoming comes back to school from home every day. If he walks 50 meters per minute, he will be six minutes late. If you walk 80 meters per minute, you will arrive three minutes early. Please work out how many meters Xiao Ming's home is from school.
Suppose Xiaoming's home is x meters away from school.
(X/50)-6=(X/80)+3
3X/400=9
X= 1200
Xiaoming's home is away from school 1200m.
3. Party B can finish a job in 5 hours; If B does it 9 hours before A, it will take 3 hours to finish it. Then, after A did 1 hour, B did it. How many hours will it take to complete?
After 5 hours, Party A can do it for 3 hours. If B does it for 9 hours before A does it, it will take 3 hours to finish it.
Explain that A's 2-hour workload is equal to B's 6-hour workload.
A's work efficiency is equal to three times that of B.
Therefore, it takes 18 hours for Party B to complete the work alone, and 6 hours for Party A to complete the work alone.
So if Party B does it after 1 hour, it will take 18-3* 1= 15 hours to finish it.
Party B will do it after 1 hour, and it will take 15 hours to complete it.
4. The pool has a water inlet pipe and a drainage pipe. If the water inlet pipe is opened separately, a pool of water can be filled in 10 hour; Open the water pipe alone, and a pool of water can be drained in 15 hours; Now there is half a pool of water, can you open the inlet and outlet pipes at the same time to fill the pool? If so, can you fill the pool in a few hours?
If the water inlet pipe is opened separately, a pool of water can be filled in 10 hour; Just turn on the water pipe, 15 hours can drain a pool of water; So at the same time, open the inlet and outlet pipes to fill the pool.
( 1/2)/[( 1/ 10)-( 1/ 15)]
=( 1/2)/( 1/30)
= 15
15 hour can just fill the pool.
5. A pool is equipped with three water pipes A, B and C. Open the first pipe for 6 hours, the second pipe for 8 hours, and the third pipe 12 hour to fill the pool. If pipes A, B and C are opened at the same time, how many hours can you fill half the pool with water?
( 1/2)/[( 1/6)+( 1/8)-( 1/ 12)]
=( 1/2)/(5/24)
= 12/5
=2.4
2.4 hours can just fill half the pool with water.
6. A pool is equipped with a water inlet pipe and a water outlet pipe. A single water inlet pipe can fill the whole pool within 30 minutes, and a single water outlet pipe can drain the whole pool within 3/4 hours. Now open two pipes at the same time, and you can fill the empty pool in a few hours.
3/4 hour =45 minutes
1/[( 1/30)-( 1/45)]
= 1/( 1/90)
=90 minutes
= 1.5 hours
Open two pipes at the same time, and the empty pool can be filled after 1.5 hours.
7.a single pipe can fill half of the pool water in 3 hours, and B single pipe can finish the whole pool water in 9 hours. Now both pipes are opened at the same time. Two-thirds of the swimming pool will be empty in a few hours.
A single open nail tube can fill half a pool of water in 3 hours and one pool of water in 6 hours.
[ 1-(2/3)]/[( 1/6)-( 1/9)]
=( 1/3)/( 1/ 18)
=6
Six hours later, two-thirds of the swimming pool was still empty.