Who can give the correct steps and answers to a Mathematics Olympiad problem in the sixth grade of p

Because every hour is 4 minutes slow, 8:30 to 12 o'clock is the hour, 4 minutes late, so at 12 o'clock this alarm time is 12 o'clock - 14 minutes = 11:46, the actual time of this alarm clock is 14 * 60 56 = 15 minutes.

So it will take another 15 minutes to point to 12 o'clock.

It takes 210 minutes from 8:30 to 12 noon standard time, 210 60 is the hour, multiplied by 4 minutes is 14 minutes.

The answer is 14 minutes.

At 12 o'clock in standard time, this clock is 14 minutes slower, that is, 11:46, then 4 minutes per hour is 4 60 is equivalent to 1 * 15 per minute slower, 14 minutes is 14 * 1 15 = 14 15, then the time required is 14 minutes slow plus the clock goes 14 minutes slow time, (14 + 14 15) minutes, I don't know if there is such a question so early in the current primary school, and I want to ask about the one in front, the clouds are light and the wind is light, (The actual time of 14 minutes of this alarm clock is 14 * 60 56 = 15 minutes, and 60 * 56 here is what it means) If you see it, you can tell me how it came.

The two brothers walked from home to school at the same time, the elder brother walked 90 meters per minute, the younger brother walked 70 meters per minute, 1 minute after departure, the elder brother found that he was missing the pencil case, so he returned the same way, and set off immediately after taking it, and arrived at the school at the same time with the younger brother, and asked them how many meters from home to school?

Set the tasks of group A as: A and group B tasks are: B Group C tasks are: C Derived from the title:

A*5 8=B*1 4=C*7 12

Multiply the above equation by 24 at the same time to get :

15 * A = 6 * B = 14 * C.

B = 15 * A 6

C = 15 * A 14

By the title, A, B, and C are three groups of tasks and 512, ie.

A + B + C = 512

A+15*A6+15*A14=512

Solution: A = 112

B = 15 * A 6 = 15 * 112 6 = 280 C = 15 * A 14 = 15 * 112 14 = 120 Group A has completed the task: 112 * 5 8 = 70

Group B has completed tasks: 280*1 4=70

Group C has completed tasks: 120*7 12=70

The three groups of A, B, and C have completed tasks = 70 * 3 = 210, and there are 512-210 = 302 (sets) of uncompleted tasks in total

Let A, B and C complete the number of sets of garment processing in each group as x

x/(5/8)+x/(1/4)+x/(7/12)=512x=70

There are still 302 sets left unprocessed.

A + B + C = 512

5 8 A = 1 4 B = 7 12 C.

A = 112 B = 280 C = 120

Each group has completed 70 years.

There are 512-210 = 302 left

A*5 8=B*1 4=C*7 12

Then A: B: C = 14:35:15

The tasks assigned by A = 512 (14 + 35 + 15) * 14 = 112 sets, each group has completed 112 * 5 8 = 70 sets.

512-70*3=302 sets without processing.

Set the set of digits x completed by A, B, and C

x (5 8) + x (1 4) + x (7 12) = 512 to get x = 70

The number of sets that are not processed is 512-70*3=302, so there are still 302 sets that are not processed.

Let the numbers of A, B, C, and tasks be x, y, and z., respectively

From the question, x+y+z=512

5x/8=1y/4=7z/12

x=6y 15

z=6y/14

x+y+z=512

That is: 6y 15 + y + 6y 14 = 512

y=280

Therefore x=112, y=120

Because 5x 8 = 1y 4 = 7z 12 70

So left: 512-70*3 302