The number of boys accounts for 60% of the class. How many% more boys than girls? How many% less girls than boys?

The number of boys accounts for 60% of the class. How many% more boys than girls? How many% less girls than boys?

First question: 50%
Second question: 20%

The number of girls accounts for 40% of the class. How many percent more boys than girls?

Boys make up half of the class
1－40％＝60％
There are more boys than girls
（60％－40％）÷40％×100％＝50％

Mathematical problems of solving the surface area of cylinder

A conical sand pile with a bottom radius of 1 meter and a height of 4.5 decimeters can be used to pave a 2 cm thick road surface on a 5 meter wide road. How many meters can it be paved?

The perimeter of a rectangular grassland is 32 meters. The known length is three times the width. How many square meters is the area of this rectangular grassland

4*12=48

Which is bigger, the 55th power of 3 or the 44th power of 4 or the 33rd power of 5?

4 ^ 444 is the largest and 5 ^ 333 is the smallest
3^555=(3^5)^111
4^444=(4^4)^111
5^333=(5^3)^111
Now the powers outside are the same, just compare the numbers inside

The speed of a train is 54 kilometers per hour. It takes 57 seconds for the train to cross a 640 meter long tunnel to find out how many meters the train is
Equation must be used

54 km / h = 15 m / S
15 × 57-640 = 215m
Answer: the train is 215 meters

Triangle ABC, ab = 8, AC = 7, E on AB, AE: EB = 3:5, f on AC, if triangle AEF is similar to triangle ABC, AF =?
Please write down the calculation process in detail

AE/AB=AF/AC
AF/7=3:8
AF=21/8

How much km is 4 light years?
Such as the title

1 light year = 9460800000000 km
4 light years = 37843200000000km

The first is the monthly fee of 10 yuan plus the call fee of 0.15 yuan per minute. The second is the monthly fee of 15 yuan
Q: how long is the call time, and the monthly cost of the two methods is the same? Because of business needs, Xiaomei's monthly call time is no less than 25 hours, which method do you think is suitable for her?

The first type: 25x60x0.15 + 10 = 235
The second: 25X 60x0.1 + 15 = 165
So it's obviously the second kind of cost-effective

As shown in the figure, it is known that the diagonal AC and BD of the quadrilateral ABCD intersect at point O, and AC = BD, m and N are the midpoint of AB and CD respectively, and Mn intersects BD and AC at points E and f respectively. Can you tell the size relationship between OE and of and prove it?