Who has a difficult math Olympiad problem? I m in the sixth grade, and the best answer is given a gr

1.A large truck and a small car drive from A to B at the same time, and the car returns immediately after arrival, and the speed increases by 50 when returningTwo hours after departure, the car and the large truck met for the first time, and when the large truck arrived at place B, the car just walked to the midpoint of the two places.

How long does it take for a car to make a round trip between A and B?

If the respective speed of time must not change, then the distance ratio is equal to the speed ratio.

Set the original speed of the car as the unit 1, the current speed is 150Then V car V cargo = 6 3 = 2 1t car T cargo = 1 2

4 (1 50) = 6 (hours).

2.Bus No. 6 in a city departs from the bus station at certain intervals. Someone was moving at a constant speed on the street and noticed that there was a No. 6 bus driving behind him every 6 minutes, and an oncoming No. 6 bus coming every 3 minutes. Ask for a number 6 bus to send out every few minutes?

v car v man 6 v car v man 3 v car v man 3 1v car 3v man 6 6 1 3 4 minutes

If a car drives from A to B, if the speed is increased by 20%, it can arrive 1 hour earlier than the original time, and if it travels 120 kilometers at the original speed and then increases the speed by 25%, it can arrive 40 minutes in advance.

40 minutes = 2 3 hours.

Original time: 1 [1-1 (1+20%)] = 6 hours, original speed [120-120 (1+25%)], 6-2 3-6 (1+25%)] = 24 8 15 = 45 km hours.

A and B are 45 6 = 270 kilometers apart.

1+102=101 Move a number to make the equation hold (note: it's just a simple number move, not a number reversal).

Solution: 1 + 10 square = 101

See Reader, 2010-14, Freedom on the Heights).

It is known that in the quadrilateral ABCD, AD:BC=1:2, the S triangle AOF:S triangle DOE=1:3, and the S triangle BEF=24 cm2, the area of the triangle AOF is obtained.

Liu Hua measured the volume of a bottle, measured the bottom diameter is 12cm, add a little water to the bottle, the water is 20cm high when it is being placed, the water is 25cm high when it is reversed, and the bottle is 30cm deep.

1.Alloys A, B, and C made of copper, iron, and aluminum, 1 kg each. In A, B, and C, the content ratios of copper, iron, and aluminum are 1:

If A, B, and C are to be made into a new alloy with a copper, iron, and aluminum content ratio of 4:5:3, how many kilograms of the new alloy will be made?

2.The tailor cuts a triangular piece of cloth from a rectangular piece of cloth. Knowing that the two inner angles of the triangular fabric are 55° and 35° respectively, how many times should it be cut in a straight line?

From now on, I'll give you ten.

Tree. You have to line up five lines. Each row must be four, how to arrange?

Answer: (Textual explanation).

Arrange them by five-pointed stars, with two trees at each endpoint and two in the middle.

Drawing representation) (no content for the time being).