1, two cyclists, 60KM apart, drive towards each other at the same time at the speed of 10KM/ hour. A bird flew out of one of the cyclists, flew to another athlete at a speed of 25km \/ hour, met another athlete and flew back to the first athlete. It flies around like this. So, finally, the bird flew.

Three hours later, the athletes met, and the bird flew for three hours, 25 times 3, =75KM.

2. Four people cross the bridge, the eldest brother takes 5 minutes, the second brother 10 minutes, the third brother takes 25 minutes and the fourth brother takes 25 minutes. It's midnight, they only have a flashlight, and people who cross the bridge have to send it back. How can they all cross the bridge in half an hour?

First, the eldest brother and the second brother had a flashlight, the third brother and the fourth brother had a flashlight, the second brother also had a flashlight, and the second brother and the eldest brother had a *** 1 hour together.

3. Say a box with 1 bacteria in it. Bacteria divide every minute, and the box of division 1 hour is full. Q: If you put two bacteria first, how long will it take to fill the box?

There are four people, A, B, C and D today, and they have to walk from the left to the right of the bridge at night. Only two people can sit on this bridge at a time, and there is only one flashlight. You must cross the bridge with a flashlight. The fastest time for four people to cross the bridge is as follows: a

2

Points; B

three

Points; C

eight

Points; D 10。 Fast walkers have to wait for slow walkers. How can I get there?

2 1

minute

Let everyone cross the bridge?

5、 125

×

four

×

three

=

2000

This formula is obviously not equal, but if two numbers "7" are skillfully inserted into the formula, this equation can be established. Do you know where these two 7s should be inserted?

6. Spring and summer

×

Autumn and winter

Summer, autumn, spring and winter, spring and winter

×

Autumn and summer

=

spring,summer,autumn and winter

Spring, summer, autumn, winter

Each represents four different numbers. Can you point out what numbers they represent?

7. A broken car has to walk two miles, one mile uphill and one mile downhill, and the average speed when going uphill is 15 mile. How quickly can you reach an average speed of 30 miles per hour on the second mile downhill? Is it 45 miles?

Mrs. Wang went to the market to sell eggs. The first man bought half the eggs in the basket one after another, and the second man bought the remaining half. At this time, there is an egg left in the basket. How many eggs did Mrs. Wang sell?

9. There are six multiple-choice questions on the test paper, and each question has three options. Results The marking teacher found that when choosing any three answers in all the test papers, the choice of one question was different from each other. How many people will take the exam at most?

10, there is a pasture grass, if you graze 27 cows, you can eat up the grass in 6 weeks; If you graze 23 cows, you can eat all the grass in 9 weeks; If you graze 2/kloc-0 cows, how many weeks can you eat grass?