Math problems, urgent! Do me a favor 5, math problems, hurry! Do me a favor

The original plan was to produce 7200 tops, but the actual production was 7200 (1+20%)=8640;

If the original plan is to produce x tops per day and take 7200 x days, then the actual production of (x+720) tops per day takes (7200 x-4) days, so (x+720)(7200 x-4)=7200 (1+20%)

The solution is x=720 (the other x=-1800 is rounded) so that the actual daily production is 720+720=1440 tents.

Solution: It actually takes x days to complete the production task

According to the title:

7200 (1+20%) x-7200 x+4 =720 Simplification: 12 x-10 x+4 =1

Solution: x1=6, x2=-8 (not in line with the topic, discarded) 7200 (1+20%) 6=1440 (top) Answer: The factory actually produces 1440 tents per day

The original plan was to produce x tents per day, but the plant actually produced x+720 tents per day.

7200/x-7200(1+

7200/x-8640/(x+720)=47200(x+720)-8640x=4x(x+720)7200x+5184000-8640x=4x^2+2880x4x^2+4320x-5184000=0

x^2+1080x-1296000=0

Solution x=720

The plant actually produces x+720=1440 tents per day.

Solution: It actually takes x days to complete the production task

7200 (1+20%) divided by x-7200 divided by x+4=720

Solution: x1 = 6, x2 = -8 (rounded).

7200 (1+20%) 6=1440 (top) A: The factory actually produces 1440 tents per day

Set 2 unknowns, x = actual production tent, y = how many days it originally took to complete.

In this way, with 2 equations and 2 unknowns, the equation can be solved.

Equation 1 The original production method 7200 (x-720)=y Equation 2 The current production method 7200*120% x=y-4x, y must be greater than 0, find x=1440, y=10 The general mathematical problem is this method, set 2 unknowns, find 2 different equations, and then solve.

In fact, there is a trick to this kind of problem, that is, it is generally assumed that the number of days y must be much less than the number of production x, so you can solve y first when solving, so easy!

The original planned number of production days is: x

Now the total production is: 7200 + 7200 x 20% = 86407200 x = 8640 x - 4 -720 calculation: x = 10 days.

8640 10-4 = 1440 top.

Now it actually produces 1,440 pieces per day.

Set X, then the original plan was X-720

The actual production volume is 7200 * (1 + 20%) = 8640. 8640 x+4=7200 (x-720) solution x=1440

Solution: (1) Set the total income of x yuan.

One-sixth x + one-fifth x + one-third x = x - 1440 seven-tenths x - x = -1440

x=4800

2) 4800 times a fifth = 960

Identification result: someone has an IQ of more than 70.

(1) 1440 divided by (one minus one-sixth minus one-fifth minus one-third), which is equal to 4800 yuan.

2) One-fifth times 4,800 minus one-sixth times 4,800, which is equal to 160 yuan.

First ask for a fraction of the salary of the construction **, according to what you said, the construction ** is one minus one-sixth minus one-fifth and then subtract one-third, the result is three tenths. The total income is 1440 divided by 3/10, which is 4800 yuan.

Second question: 4,800 yuan multiplied by (one-fifth minus one-sixth) equals 160 yuan.

1 - one-sixth - one-fifth - one-third = 30 minutes long 1440 divided by 9 thirties = 4800 yuan.

A: The total income for this month is 4,800 yuan.

4800 6/6 minus 4800 1/5 = 4800 (1/6 minus 1/5)=

4800 1/30 = 160 yuan.

A: $160 more.

Addendum: The second question seems to be how much less is it?!

Uh,I don't know if it's right.,It's done.,Check it.,By the way, you want to add points, oh, if it's not right, can you add typing points?

As shown in the figure below, it is analyzed

A, B, and C take turns to work in three sequences, the blue line in the figure represents the part where the three people take turns to work for the same time (the same job, so the three sequential working hours and workload are the same), and the red part represents the part that is not enough for the three people to take turns to work for the same time (the workload is the same, if enough three people take turns to work for the same time, then no matter which order, the time should be the same).

Since the order of A, B and C is finally completed in whole hours, it can be divided into two situations: first, the remaining workload (red part) is completed by A alone, and the working time is 1 hour;Second, the remaining workload (red part) A and B are completed together, and the working time is 1 hour each, a total of 2 hours.

Answer from this. Let B work alone for a few hours, and the work efficiency is 1 a;C needs b hours to work alone, and the work efficiency is 1 b;It is also known that A needs 6 hours to work alone, and the work efficiency is 1 6.

Situation 1: In the order of A, B and C, the remaining workload is completed by A alone, the working time is 1 hour, and the workload is 1 6;

According to the order of B and C A is more than the time of A and B C, so the remaining workload is completed by B and C, B works for 1 hour, C works for hours, the workload is 1 6, B works 1 a, and C works 1 b, so 1 a + 1 2b = 1 6;

According to the order of C, A and B, it takes more hours than A, B and C, so the remaining workload is completed by C and A, C works for 1 hour, A works for hours, the workload is 1 6, C works 1 b, and A works 1 6, so 1 b + 1 6 * 4 = 1 6;

Solve the system of equations {1 a+1 2b=1 6,1 b+1 6*4=1 6}

Get a=48 5, b=8

Therefore, it takes time for three people to type a manuscript together.

1 (1 6 + 5 48 + 1 8) = 48 19 (hours).

Situation 2: In the order of A, B and C, the remaining workload is completed by A and B, the working time is 1 hour each, a total of 2 hours, the work efficiency of A is 1 6, the work efficiency of B is 1 a, and the workload is 1 6 + 1 a;

According to the order of B, C and A, it takes more hours than A, B and C, so the remaining workload is completed by B, C and A, B works for 1 hour, C works for 1 hour, A works for hours, B works for 1 a, C works for 1 b, A works 1 6, and the workload is 1 a+1 b+1 6*2;

According to the order of C, A and B, it takes more hours than A, B and C, so the remaining workload is completed by C, A and B, C works for 1 hour, A works for 1 hour, B works for hours, C works for 1 b, A works 1 6, B works 1 a, and the workload is 1 b + 1 6 + 1 4a;

The system of equations {1 a+1 b+1 6*2=1 6+1 a,1 b+1 6+1 4a=1 6+1 a}

The solution yields a=9, b=12

Therefore, it takes time for three people to type a manuscript together.

1 (1 6 + 1 9 + 1 12) = 13 36 (hours).

As can be seen from the title, A is completed in 6 hours alone, and A's ergonomics is 1 6

Start Analysis:

If the last person is C in the order of A, B and C, the three people take turns equally and the number of hours is a multiple of 3.

Regardless of the other order, the number of rotations of the three people is exactly the same as in the first case, and the same number of times will end when it is the same as in the first case.

So, the last person in the first case cannot be C, only A or B.

Next, let's assume that the last person is A.

Compare 3 cases:

1, A, B, C... CArmor.

2, B C A... Armor. Ethyl propylene (

3, C A B... B|C (

The first 3 cases to the vertical line have completed the round of integers, and the workload is the same. After comparing the vertical lines.

From 1,3, it can be seen that the workload of A for one hour = one hour for C + 4 hours for A1.

C is 3 4 of A, A is known to be 1 6, C is 1 6 3 4 = 3 24

From 1,2, we can see that A = B + C 1 2, B = A-1 2C = 1 6-1 2 3 24 = 5 48

A, B and C work at the same time, and the ergonomic efficiency is 1 6 + 3 24 + 5 48 = 19 48

It takes 48 19 = hours to complete the work.

Also assume that the last person is B.

Compare 3 cases:

4, A, B, C... CA and B.

5, B C A... Armor. B C A (

6, C A B... B|C A B (

The first 3 cases to the vertical line have completed the round of integers, and the workload is the same. After comparing the vertical lines.

From 4,5, it can be seen that A + B = B + C + 1 2A.

C = 1 2 A.

C is 1 2 of A, A is known to be 1 6, C is 1 6 1 2 = 1 12

From 5,6, we can see that B + C + 1 2 A = C + A + B 1 4, and both sides eliminate B + 1 2 A = A + 1 4 B.

3 4B = 1 2 A.

B = 2 3 A = 2 3 1 6 = 1 9

A, B and C work at the same time and the ergonomics is 1 6 + 1 12 + 1 9 = 13 36

It takes 36 13 = hours to complete the work.

So the result is 48 19 (hours) or 36 13 (hours.

The one sent last night has already been given.

If the product of two digits is an odd number, then ten and sum are odd numbers.

The single digit is an odd number: 1, 3, 5, 7, 9; Ten digits are odd numbers: 1, 3, 5, 7, 9 multiplication principle can be obtained, a total of 5*5 = 25 basic events.

The total number of basic events is 9*9=81 basic events.

p=25/81

Similarly.

1.There are 81 numbers in total.

Because the product is an odd number, both numbers are odd.

The probability is 25 81

2.Both numbers are odd or even.

Probability 41 81

This doesn't seem simple. The first one should be 25%, the second should be 41%, and the third should be 75%.