Urgent! Urgent! Urgent! 30 points bounty, 5th grade fraction decimal simple arithmetic Olympiad prob

1. On the first day of school, every two students meet and shake hands with each other, how many times do the 40 people in the class shake hands?

2. The second term of an equal difference series is 2 8, and the third term is 3 1, find the 15th term of this equal difference series.

3. There are 36 students in the second class of the fifth grade, and the class leader Wu Hong went to buy a picture book for everyone, one for each person. When I came back, I forgot to count the money, but I only remembered that it was 1 1 yuan. Q: Each picture book is a yuan.

4. The oil in the east oil inventory is 6 times that of the oil in the west oil, if the two oil depots each increase 30 tons of oil, the oil in the east oil will be 3 times the oil in the west oil stockpile, how many tons of oil in the two oil depots?

5. A six-digit abcdek, multiplied by e, the original number is kabcde, what is the original number? (Different letters represent different numbers) what the original number is.

6. 500 people from Qingquan Primary School participated in the entrance ceremony of the sports meeting, with a line of 20 people per line, the distance between the two lines was 3 meters, and the rostrum was 18 meters, and they passed the rostrum at a speed of 30 meters per minute, how many minutes did it take.

7 can be turned into a circular decimal, ask what is the number in the 1995th place after the decimal point of this circular decimal? What is this number.

9. The three sides of a triangle are three consecutive two-digit even numbers, and the sum of their mantissa numbers is divisible by 7 to find the maximum perimeter of this triangle.

10. There is a fraction, if the numerator and denominator are added to 1, the fraction becomes 1 2, if the numerator and denominator are subtracted by 1, the fraction becomes 2 5, find this fraction.

11. One day, a jewelry store in a certain city was stolen from diamonds worth tens of thousands of yuan. After reporting the case, after three months of investigation, it was ascertained that the perpetrator must be one of A, B, C, and D. After interrogation, the confessions of the four men were as follows:

A: On the day the diamond was stolen, I was in another city, so I'm not a criminal.

B: D is a criminal.

C: B is a thief, and three days ago, I saw him selling a diamond on the black market.

D: B has an enmity with me and intends to frame me.

Because of the inconsistencies in the confessions, it is impossible to determine who is the culprit.

After the panic test, it is known that only one of the four people is telling the truth, so who is the criminal?

12. There are 253 students in the fifth grade of Qingfeng Primary School, and the school has organized a math group, a recitation group, and a dance group, and stipulates that each person participates in at least one group and at most two groups, so how many people participate in the same group at least? 1, if you write the simple as a 0), there are 3 decimal places below.

A = zero) 12, b = one hundred 0) 025, c = 0) 08

Find a b(b c)-(a+b)=?

4.The sum of the two numbers is, if the decimal point of the smaller number is moved one place to the right, it is equal to the larger number, what is the decimal place?

5.When the decimal point of a number is shifted to the left by two places, the resulting number is smaller than the original number, what is the original number?

0)04, b = 0)05

a+b=( )a-b=( )

a×b=( )a÷b=( )

There is a six-digit number: ABCDEF multiplied by 3 equals BCDEFA, find: ABCDEF equals what?

After solving it, you will find the mystery in it, and this number is very familiar.

The class of 52 people took a math test, each of them did 5 questions, and a total of 181 questions were correct, and each person was known to have done at least one question correctly. There are 7 people who get one question right, there are just as many people who get two questions right and three questions right, there are 6 people who get all 5 questions right, and how many people get 4 questions right?

There are 13 people who got 1 and 5 questions right, with a total of 37 questions.

There are 39 people left, 144 questions.

There are as many people who get 2 and 3 questions right, set to x people each.

Then there are 39-2x people who get 4 questions right.

It can be seen that 2x+3x+4(39-2x)=144

x=4 So 31 people get 4 questions right.

You can go to Xinhua Bookstore and buy the A or B version of the Primary School Olympiad from Shaanxi Province for the third and fifth grades, which has a lot of content very good, and I bought it for my son.

Is it necessary? Just buy a book and read it.

I'll give you a link and see for yourself.

Average: (1*8000+2*6000+5*4000+32*2000) (1+2+5+32)=2600

Median: 2000 (40 people in total, in descending order, the average of the salaries of the 20th and 21st people is 2000).

Mode: 2000 (the number with the most occurrences).

Simple arithmetic of the law of addition (1).