In the final exam, Xiaoming's average score in Chinese and mathematics is 90. After counting English scores, the average score is 92. How many points did Xiaoming get in the English exam?

Answer and analysis: 92×3-90×2=96 (points)

Summary and average problem is an important means to solve the problem from the perspective of total number.

How can I open the lock?

The administrator of the new teaching building holds 15 different keys to open 15 classroom station, but he doesn't know which key opens which door. At most, he can match the key with the classroom door lock.

Answer and analysis:

In most cases, except the matching key, the other keys can't be opened before the last test drive.

So 1 key will be tried at most 14 times; Test the second hand at most 13 times; 14 handle is tested at most 1 time; The first pair 14 and the second pair 15. So use the key to match the classroom door lock, and try to open14+13+…+1= (14+1)+(13+2)+(/kloc-0)

What is the salary of mentoring?

There are two people working on the construction site. Because one is an apprentice and the other is a mechanic, the salary is different. The wages of mechanics are $20 more than those of apprentices, but the difference between them is $265,438 +0. What do you think their salary is?

Answer and analysis:

Suppose the comparison standard between technicians and apprentices is $ 1. Then the mechanic's salary is 20.50 yuan, and the apprentice's salary is 50 yuan. Compared with $ 1, the wages of technicians are positive and those of apprentices are negative, with a difference of $2 1. In fact, the salary of a mechanic is 20 dollars higher than that of an apprentice.

Chapter IV: How many acres of land are there respectively?

A production team has 208 mu of cultivated land, and it is planned to make irrigated land 62 mu more than dry land team. How many mu should irrigated land and dry land be?

Solution: let the mu of dry land be x mu.

208-x=x+62

x=73

Irrigated land: 208-73= 135 mu

Chapter 5: How many cars can you see?

A and B are two bus stops, and it's uphill from A station to Mile Mile. Every morning from 8: 00 to 1 1, a bus leaves from Station A and bilibili at the same time every 30 minutes. It is known that it takes 105 minutes to get from station A to station B, and it takes 80 minutes to get from station B to station A..

(2) How many cars can the driver of Station A see at least from the mile?

Solution: Method 1: (1) The driver from Station A sees two kinds of vehicles. One is all the vehicles that leave from Miley Miley but haven't arrived at Station A before his departure, that is, all the vehicles that depart from Miley Miley within 80 minutes before departure, and the other is all the vehicles that depart from Miley Miley Miley during the period from his departure to his arrival. That is, all vehicles that leave the mile within 105 minutes after departure. That is to say, the driver can see the vehicles from the mile to the mile from 80 minutes before driving to 105 minutes after driving. In fact, in this 185 minute, there are only 60 minutes and 30 minutes before the departure, so drivers who leave from Station A at 8: 30, and drivers who leave from Station A at 8: 00 to 10: 00 can see five cars leaving from Miley, while drivers who leave from Station A at 9:00, at 8: 00.

(2) 1 1 Drivers who leave A can only see the cars that left before11but have not yet arrived at Station A, that is, 10: 00,/kloc-0: 30 and/kloc-0.