10 6th grade math engineering questions with answers. 30

1. Dig a canal, plan to dig 60 meters per day, it can be completed in 24 days, and it is actually completed 4 days ahead of schedule.

Solution: 60*24 (24-4)=72 (m).

2. Master Li and Master Wang process a batch of parts at the same time, and the two work together for 6 hours to complete, it is known that Master Li processes 50 pieces per hour, and it takes 11 hours for Master Wang to do it alone, how many pieces does Master Wang process per hour?

The number of parts processed by Master Wang per hour is: 50*(66 5) 11=60 (pieces).

3. Make a batch of clothing, A does it alone for 8 days, B does it alone for 10 days, and after the two teams work together for a period of time, B does it alone for 1 day, how many days do the two teams do together?

Solution: (1- 1 10) 1 8 + 1 10) = 49 (days).

4. A pool is equipped with two water pipes A and B, a single pipe can be filled with a pool in 5 hours, and a single pipe B can be filled with a pool in 4 hours.

Solution: 1 (1 5 + 1 4) = 20 9 (hours).

5. To process a batch of parts, A alone takes 8 hours to complete, B alone takes 10 hours to complete, A and B cooperate for 4 hours to process 207, how many parts are there?

Total: 207 4 40 9=230 (pcs).

6. To build a kilometer-long highway, 630 meters were built in the first 7 days, according to this calculation, how many days will it take to complete this section of the road?

Solution: (1800-630) Shijudong 630 7) = 13 (days).

God's ignorant darling, hello:

A and B combined for 4 days, and the attack was completed:

Team C completed all 7 days after they came in, and the three teams completed every day

1 3 10) sell sedan brother 7 1 10

Teams A, B and C started to repair this road at the same time to complete the need:

1 1 10 10 (day).

A takes 4 days, and B does another 24 days to complete.

A can be completed in 16 days, B in 6 days.

A 16-4 = 12 days of work, equal to B 24-6 = 18 days of work.

B 6 days of work, A needs: 12 (18 6) = 4 days.

A is done separately and requires: 4 + 16 = 20 days.

B is done separately and requires: 20 4 6 = 30 days.

A 10 days, complete: 1 20 10 = 1 2

There is 1-1 2 = 1 2

B also needs: 1 2 1 30 = 15 days.

Suppose A does x work a day, and B does y work a day. If the total workload is constant, the following equation can be obtained from the title:

4x +24y = 6y + 16x = 10x + y is given by the first equal sign: 12x = 18y

i.e.: 2x = 3y;

Then: 4x + 24y = 4x + 6x - 9y + 24y = 10x + 15y

Therefore, if A does it for 10 days and B does it for 15 days, it can be completed.

Because A does it alone for 4 days, B then does it for 24 days. Or B does 6 days, A then does 16 days can also be completed, so A does (4 + 16) days, plus B does (24 + 6) days, can complete 2 times the work, so to complete twice the project, it takes A 20 days and B 30 days, that is, it takes 10 days for A and 15 days for B to complete the double project, so the answer is 15 days.

Hope it helps!

15 days. I don't know if I learned to set the unknown quantity x,y. Let's make A do x every day and B do y every day

4x+24y=6y+16x, find y=(2 3)x b and then do a day.

10x+ay=4x+24y, then 10x+a(2 3)x=4x+24*(2 3)x, get a=15

The efficiency of disarming armor is x

1-4x)*6 24+16x=1 The solution yields x=1 20

1-10x)*24 (1-4x)=15 days.

16-(24-16)/(6-2)x4=0

B then does it in 0 days to complete.

A job is completed in 30 days for A and B cooperation, 40 days for B and C to complete, and 60 days for A and C to cooperate. If A, B and C do it together, it will take (80 3) days to complete the whole work, and if C alone will complete the work, it will take (240) days.

80 for 3 days.

240 days.

How many days does it take for the cooperation between B and C to complete?

There should be a question ahead, but it seems impossible to do this.

The total project is set to 1

A, B, and C are completed separately, each for x days, y days, and z days.

x+y=1 30 y+z=1 40 x+z=1 60 calculate 1 divided by x+y+z to get the cooperation of 1 divided by z to get C alone.

1.It takes 10 (1 3) = 30 days for team A to do it alone, 1 30 for team B to do it alone 15 (1 3) = 45 days, and the time required for the first 1 3 project at a speed of 1 45 is (1 3) (1 30 + 1 45) = 6 days, and the remaining 2 3 days are required for team A to complete alone.

2 3) (1 30) = 20 days.

Pooling time = 6 + 20 = 26 days.

2.The speed of cooperation between teams A and B = (2 5) 6 = 15 1 The speed of team A = [3 5-6 * (1 15)] 4 = 1 20, so the number of days required for team A to do it alone is 1 (1 20) = 20 days 3If B's speed is 1, then A's speed is 1 (1+1 4)=4 5 When B completes 40 more parts than A, then B does the number of parts.

40 (1-4 5) = 40 (1 5) = 200, A is 200-40 = 160, and the total number is 160 + 200 = 360.

4.The water injection rate of the C pipe is.

1-2*1 12-2*1 10) 2-1 12-1 10=2 15, so the time required for the single opening and filling of water in the C tube = 1 (2 15) = hour 1 4 1 20 = 5

If a project A takes 5 days to complete, 10 days to complete, and 20 days to complete, it means that the project is considered as a whole, A.

To divide the whole into five equal parts, it will be completed in five days, and one of the five parts will be completed in one day, that is, one-fifth. In the same way, B will finish alone, and he will complete a tenth of it in a day. C will complete one-twentieth of the day in one day. If you ask how many days will the cooperation between A and B be completed?

Just use the total amount of work 1 (1 5 + 1 10).

If you ask three people how many days to complete.

If A does it for two days, how many days will it take for B and C to do the rest?

We haven't learned engineering yet.

A: 63-48 = 15 days B: 48-28 = 20 days A: B = 15:20 = 3:4 That is, in the daily work, A does 4/7 B does 3/7

Then: B alone takes 48 3/7 = 112 days A 48 4/7 = 84 days.

After 42 days, the workload of A is 42 84 and B needs 112 * (1-42 84) = 56 days.

If A and B cooperate, it takes 48 days to complete, and it can be seen that the cooperation efficiency of the two is 1 48, and if both of them do 28 days, 1-28 48 = 20 48, A does 35 days = 20 48 = 5 12

A day = 1 84

B 1 48-1 84 = 3 336 = 1 1121-1 84 * 42) divided by 1/112 = 56