Sixth grade Olympiad, rookie don t enter, sixth grade Olympiad, urgent!

Solution: Let's assume that 100 students will take this exam. Then 19, 9, 26, 11 and 15 of these 5 questions got it wrong. A total of 19 9 26 21 15 90 (questions) were made wrong

If the pass rate is the highest, each person should be asked to get no more than 2 questions wrong. 90 people can only get 1 question wrong each, so that the pass rate of the exam can reach 100%.

If the pass rate is the lowest, as many students as possible should be allowed to do 3 questions incorrectly (plastic surgery or above), 90 3 30. So there may be 30 people who did it wrong and didn't qualify.

This is possible, for example, with 9 people getting it wrong, 6 people getting it wrong, 4 people getting it wrong and 11 people getting it wrong.

So the pass rate is 100% at the highest and 70% at the lowest.

Liang Liang, you can list a square, and then I'll tell you in the class, it's definitely 81% 100% guaranteed.

I'm a small boat boat.

The probability problem, like using assumptions to assume 100 people, multiply the number of people by the score, and 19, 9, 26, 11, and 15 people get wrong, respectively. A total of 19 9 26 21 15 90 (questions) were made wrong

Later, it was slowly calculated that the highest pass rate was 100% and the lowest was 70%.

The simple problem of probability is that the numbers given are hard to calculate.

Go to the metropolis that is too high.

It's so simple, with probability!!

Plus, I'll tell you how to use probability.

Human ergonomics and, for:

1 2 + 1 6 + 1 10 + 1 3 + 1 15) 2 = 7 12bcde4 artificial efficiency, is: 1 3 + 1 15 = 6 15 7 12 so a is water inlet, the work efficiency is: 7 12-6 15 = 11 60b is water inlet, and the work efficiency is:

1 2-11 60 = 19 60c for water discharge, the working efficiency is: 19 60-1 15 = 1 4d for water inlet, the working efficiency is: 1 6 + 1 4 = 5 12e for water discharge, and the working efficiency is:

5 12-1 3 = 1 12 The highest water injection efficiency is d, and the filling requirement: 1 5 12 = hours The highest water discharge efficiency is c, and the venting requirement: 1 1 4 = 4 hours 2

Take A and B as 1

It turns out that the speed ratio of Xiao Ming and Xiao Liang is 5:6

When they met for the first time, Xiao Ming traveled the whole process of 5 (5+6)=5 11, that is, the distance between the first encounter point and A was 5 11

When Xiao Liang arrived at A, Xiao Ming traveled the whole journey of 5 6, and the distance between Xiao Ming and B was 1-5 6 = 1 6

At this time, Xiao Liang speeds up, and the speed ratio between Xiao Ming and Xiao Liang is:

5:6 (1+1 4)=5:15 2=2:3 Xiao Ming finished the remaining 1 6, Xiao Liang did it again:

At this time, the distance between Xiao Ming and Xiao Liang is: 1-1 4 = 3 4 and then Xiao Ming also speeds up, and the speed ratio of Xiao Ming and Xiao Liang is:

2 (1+1 5):3=12 5:3=4:5 When the two met for the second time, Xiao Ming did it again:

The distance between the second encounter point and A is:

The distance between the two meeting points is:

The distance between A and B: 35 7 33 = 165 km.

1. Assuming that ABCDEs are all filled with water, the task of filling a pool of water is set to 1, and the corresponding water injection speeds are A, B, C, D, and E respectively

With the above information, the following equations can be listed:

2*（a+b）=1

6*（c+d）=1

10*（e+a）=1

3*（d+e）=1

15*（b+c）=1

Find this system of equations and get the following answer:

a=11 60 per hour.

b = 19 60 per hour.

c = -15 60 per hour.

d = 25 60 per hour.

e = -5 60 per hour.

The positive value is water injection, and the negative value is water release, that is: A needs 1 (11 60) = hours to fill the pool, B needs 1 (19 60) = hours to fill the pool, C takes 1 (15 60) = 4 hours to empty the pool, D takes 1 (25 60) = hours to fill the pool, and E takes 1 (5 60) = 12 hours;

The most efficient water injection is the D water pipe, which only takes hours; The most efficient way to discharge water is the C water pipe, which only takes 4 hours.

2. Solution: The distance ratio of Xiao Ming and Xiao Liang = speed ratio = 5:6

The first encounter is 5 11 from the ground of the first place

Xiao Ming arrived at place B and traveled the whole journey of 6 11

Then Xiao Liang traveled the whole course of 6 11 6 5 = 36 55

At this time, Xiaoliang is 36 55-5 11 = 1 5

The distance between the two is 1-1 5 = 4 5

In this case, the velocity ratio = 5 (1+20%): 6 = 1:1

Then the second place of encounter is 1 5 + 4 5 1 2 = 1 5 + 2 5 = 3 5

So the distance between A and B = 40 (3 5-5 11) = 40 (8 55) = 275 km.

I've done this before, you see.

Oh my God, what kind of topic is this, your child is amazing!

Guo Guo gives one to Zhou Zhou, and Guo Guo has a total number: 1 (1+1 2)=2 3 Zhou Zhou gives Guo Guo one, Guo Guo has a total number: 1 (1+1 3)=3 4 Compared with the two times, the difference between the stones in Guo Guo's hand is 2.

There are two in total: 2 (3 4-2 3) = 24.

If Guo Guo takes a stone from his hand and gives it to Zhou Zhou, then the stone in Zhou Zhou's hand is one-half of the stone in Guo Guo's hand.

At this time, the number of stones in Guo Guo's hand was (x+1) (1 2)=2(x+1), and there was originally 2(x+1)+1=2x+3

If Zhou Zhou took a stone from his hand and gave it to Guo Guo, the number of stones in Zhou Zhou's hand would be one-third of the number of Guo Guo's stones.

x-1)/(1/3)=2x+3+1

There is the equation 3x-3=2x+4

x=7 then Zhou Zhou has 7 stones, Guo Guo has 17 stones, a total of 24 stones.

Solution: Before Guo Guo had x stones in his hand, Zhou Zhou had y stones in his hand, and it can be obtained from the inscription ( x - 1 ) 2 = y + 1....x + 1 )/3 = y - 1...

Subtract the formula to get x = 17, and substitute x into the formula or to get y = 7, so the two have a total of x + y = 24 stones.

Let Guo Guo have x stones in his hands, and Zhou Zhou has Y stones in his hands.

1/2（x-1)=y+1

1/3 (x+1)=y-1

x=17;y=7

Because the position of the hour hand and the minute hand are interchanged for more than 2 hours, the minute hand must start in front, assuming that the angle between the hour hand and the minute hand at the beginning is a, then the hour hand has traveled a degree, and the minute hand has traveled 360 * 3-a degrees, and because the minute hand has traveled every "360 degrees", the hour hand has traveled 360 degrees 12 = 30 degrees. (One hour for the minute hand to go in one circle.) The instant hand goes 360 per degree, and the minute hand goes 360 = 12 degrees.

So there is another 12a=360*3-a

The solution is a = 1080 13 degrees.

Then the minute hand has gone 360*3-a=1080*12 13 degrees, then the time has passed (1080*12 13) 360=hours are minutes.

Set the army to leave the house for x minutes.

Since the hour hand travels every minute and the minute hand travels 6° per minute, they go a total of 3 turns.

The cost of commodity A is x yuan, then the cost of commodity B is 220-x yuan [x*(1+30%)+220-x)*(1+20%)]x=60

The cost of Class A goods is 60 yuan.

A costs x yuan, and B is 220-x

x*130%*

Then solve the equation.

A + B = 220

A, B, A, (1+30%), B, B(1+20%)

A, B, A: (yuan).

The cost of Class A goods is 60 yuan.