a . 2000 15 b . 2222 15 c . 2020 15d . 2200 15

This question is simple. Method 1: Direct calculation does not require much effort, but unfortunately, if you are not careful in the calculation process, mistakes may occur. Method 2: Round up (200000-1)+(20000-1)+(200-1) = 2228. Here, what I want to introduce to you is a fast addition, which can be calculated in your mind or written on paper, and is suitable for this kind of problem and data analysis. As far as this problem is concerned, the rapid addition is as follows: units: 9, 9, 9∣5 into 4; The ten digits are: 9, 9, 9, 1∣ 1 into 4; Hundreds: 9, 9, 9, 1 ∣ 2 into 3; Thousands: 9,9, 1 ∣ 2 into 2; Ten thousand digits are 9, 1∣2 1, and one hundred thousand digits are 1∣2, so we get 2222 15. The formula is as follows (it may not be suitable at first, but if you try it, you will find that this method is actually very fast):

9,9,9,9,9∣5→4

9,9,9,9, 1∣ 1→4

9,9,9, 1 ∣2→3

9,9, 1 ∣2→2

9, 1 ∣2→ 1

1 ∣2

=2222 15

2. A workshop originally planned to install 300 machines 15 days, but now it has to be completed 5 days in advance. On average, how many more machines are installed every day than originally planned? ()

A. 10

Engineering problems: (Engineering problems are problems involving planning and practice).

According to the original plan, 300/ 15=20 machines should be installed every day (daily work efficiency). Now 300 units are completed five days ahead of schedule, which means that 300 units are installed in 10, so the daily work efficiency is 300/10=30. So now the average daily work efficiency is higher than the original plan.

3. Today is Wednesday. From today, the100th day is ().

Today is Wednesday, and it will be () in 100 days/100 days.

A.wednesday, b, thursday, c, friday, d and saturday

This is a typical problem that needs to be introduced emphatically in mathematical operation-the weekly problem, or a little bigger, the weekly problem in the periodic law problem-what is the periodic law in the weekly problem? We know that a week is seven days, that is, seven days is a cycle and the dividend is seven. It was supposed to be Wednesday, so it will be Wednesday after seven days; This kind of problem, you should know that the nth day is the day before the nth day. For example, if it is Friday after n days, then the nth day is Thursday. In this question, today is Wednesday, which means today is the first day, 100/7= 14, so the 98th day is Tuesday, the 99th day is Wednesday, and the 100th day is Thursday. If today is Wednesday, what day is 100? Similarly, the first day should be Thursday, the 98th day is Wednesday, the 99th day is Thursday, and the100th day is Friday.

4. The value of100+95+90+is ().

1000

Method 1: This is a arithmetic progression, 100, divided into 20 parts for every 5 parts, or n=20, and arithmetic d=-5, and then according to arithmetic progression formula sn = na1+1/2n (n-1) D. Method 2:

5. A ball falls freely from the height of 100 meters, and jumps back to half the original height after landing every time. When landing for the third time, the distance traveled by * * * is () meters.

150

The problem of falling body bounce-the problem of falling body bounce has a property that the height it bounces after falling, that is, the distance it travels after bouncing, will always be lower than the height when it starts to take off and fall.

This topic belongs to the problem of falling body bouncing. The first bouncing distance of the ball is100+50; Distance traveled by the second complete bounce: 50+25; Distance of the third complete bounce: 25+12.5; The question is how far the ball has traveled when it landed for the third time, so we know that we don't need to complete the whole bouncing process for the third time, just remember the distance when it landed. Therefore, the total distance traveled by * * * is100+50+50+25+25 = 250m.

6. The size relationship of-2/3, -4/7 and -7/9 is ()

A.-4/7 >-2/3 >-7/9 B.-7/9 >-4/7 >-2/3

C.-2/3 >-7/9 >-4/7 days -4/7 >-7/9 >-2/3

We know that the larger the negative number, the smaller it is, that is, the farther away from the origin, the smaller the deviation to the left. -2/3 is about -0.67, -4/7 is about -0.57, and -7/9 is about -0.77 period, so we know that-4/7 >; -2/3 >-7/9; Of course, we can also compare the sizes with the same scores, so after the same scores, they are -42/63, -36/63, -49/63, obviously,-4/7 >; -2/3 >-7/9 。

7.523+746+589+423=()

228 1 2 180 c 2280d 2380

Method 1: mantissa method, which is not introduced here; Method 2: It is the quick addition recommended above.

The formula is as follows: 3 6 9 3∣ 1→2.

2 4 8 2∣8→ 1

5 7 5 4∣22

=228 1

8. There is a one-meter-long rope, and two-thirds of the rope must be cut off every time. How many meters are left after three cuts? ()

1/9 c . 1/27d . 8/8 1

One-meter-long rope is cut by two-thirds every time. We know that after the first cutting, there is still1-2/3 =1/3m, after the second cutting, there is still1/3-2/9 =1/9m, and after the third cutting, there is still 65,438m.

9. There is a plane traveling between City A and City B.. Due to the influence of wind speed, it takes 4 hours to arrive and 5 hours to return. It is known that the distance from city A to city B is 1000 km. What is the wind speed? ()

22.5 kilometers per hour

C.20 km/h D. 3 km/h

Travel problem-three quantities should be grasped in the travel problem, namely speed, distance and time, that is, s=vt. Also pay special attention to the problem of running water (the problem of running water will involve wind speed-downwind; Against the wind)

According to the meaning of the question, this question can list the solutions of binary linear equations. Suppose the aircraft speed is v 1 and the wind speed is V wind, then v 1+v wind = 250; V 1-v wind = 200; Simultaneous solution of v wind = 25 km/h.

10.325+ 135+675+265=()

a 1500 b 1400 c 1300d 1200

The problem is simple, just do the math. Method 1: (325+675)+(135+265) =1000+400 =1400; Method 2: The quick addition mentioned above.