To harvest a piece of wheat, it takes 8 hours for a to finish harvesting, and the working efficiency of B is 80% of that of A How many more hours will it take to finish harvesting this piece of wheat?

Let's say that the velocity of a is 1 / 8
B is 1 / 8 * 80%
1 divided by this
That is 10 hours

The specific topics are as follows:
To complete a project, if everyone's work efficiency is the same, three people work together for one day more than four people work together. Two people work together for several days to complete

6 days

How to do the exercises about engineering work efficiency in Grade 6 of primary school?

(1) General formula:
Work efficiency × man hour = total work; work amount △ man hour = work efficiency; work amount △ man hour = man hour
Working efficiency × working hours = total amount of work △ working efficiency = working hours
Total amount of work △ working time = working efficiency
(2) The formula for solving engineering problems by assuming that the total amount of work is "1" is as follows
1 △ working time = fraction of the total amount of work completed in unit time;
1 △ what percentage of work can be completed per unit time = working time
(Note: to solve engineering problems with hypothesis method, you can arbitrarily assume that the total amount of work is 2, 3, 4, 5 Especially when the total amount of work is assumed to be the least common multiple of several working hours, the fractional engineering problem can be transformed into a relatively simple integer engineering problem, and the calculation will become relatively simple.)

Judge whether the two quantities of each question are in inverse proportion, and explain the reasons

Total amount of work = work efficiency × work time
Now the total amount of work is certain
Therefore, the multiplication of work efficiency and work time is a fixed value
So it's inversely proportional

Judge whether the two quantities in each question are in inverse proportion, and make it clear: 1
1. A certain amount of work, work efficiency and working time. 2. A certain distance, speed and time
3. The floor of an electric classroom should be paved with tiles, the area of each tile and the number of tiles needed
Come on. It's urgent

Work efficiency × work time = total amount of work (certain) is inversely proportional
When the distance of the car is fixed, the speed of the car × the time of the car = the inverse proportion of the distance of the car
The area of each floor tile × the number of bricks needed = the area of the classroom (certain) is inversely proportional

On the efficiency of practical problems
Copy a report. If you copy 20 words per minute, it will take several hours to finish. When you finish 5 / 2, the efficiency will be increased by 40%. As a result, it will be finished half an hour earlier than the original plan

Time is an equal factor
And the number of words is a constant factor
It's very simple. Let's set the total number of words as a
In this way, the remaining words are 3 / 5 * a, and the remaining speed is 28 words (20 * 140 *)
(3/5*A /28+30)*20*2/3=2/5*A
Solve the equation a = 3500
The equation listed is the word number equation, please think more

A clothing factory is preparing to process 600 sets of sportswear,
The work efficiency is increased by 20% compared with the original plan. As a result, the task is completed 2 days ahead of schedule. Then, how many sets of clothes are planned to be processed every day? How many sets of clothes are actually processed every day?

Set X sets per day in plan, and X (1 + 20%) is 1.2x sets per day
600÷x-2=600÷1.2x
Multiply 6x on both sides
3600-12x=3000
12x=600
x=50
1.2x=60
A: it is planned to have 50 sets per day, but actually 60 sets per day

A clothing factory is going to process 400 sets of sportswear. After 160 sets of sportswear are processed, new technology is adopted to improve the work efficiency by 20% compared with the original plan. As a result, it takes 18 days to complete the task. How many sets of sportswear are processed in the original plan?

Suppose that the original plan is to process x sets per day, from the meaning of the question: 160x + 400 − 160 (1 + 20%) x = 18. The solution is: x = 20. It is tested that x = 20 is the solution of the original equation. Answer: the original plan is to process 20 sets per day

A clothing factory produced 4500 sets of sportswear in February, 10% less than that in January. How many sets less than that in January?

4500 (1-10%) - 4500 = 4500 △ 0.9-4500 = 5000-4500 = 500 (sets) a: 500 sets of sportswear were produced less in February than in January

There are 77 1's and 51 0's in 128 numbers. Calculate the probability of 1's and 0's, expressed in percentage. Please write down the calculation process

1 / 128 * 77 * 100% = 60.16%
The probability of 0 is 1 / 128 * 51 * 100% = 39.84%

To harvest a piece of wheat, it takes 8 hours for a to finish harvesting, and the working efficiency of B is 80% of that of A How many more hours will it take to finish harvesting this piece of wheat?