There are 370 sixth grade students in a school. This year, 10% of the boys transfer out and 5% of the girls transfer out. This is the same number of boys and girls. How many sixth grade students are there now

There are 370 sixth grade students in a school. This year, 10% of the boys transfer out and 5% of the girls transfer out. This is the same number of boys and girls. How many sixth grade students are there now

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Suppose the male is x and the female is y
that
X+y=370
x(1-10%)=y(1-5%)
What meets this condition is
x=190
y=180
90% of 190 is 171
95% of 180 is 171
Now there are 342 students

The sixth grade of Guangming primary school held a calligraphy competition. The number of participants in the competition accounted for four seventh of the total number of students in the whole year. Later, two more students took part in the competition. This is the reason why they participated in the competition
The ratio of the number of competitors to the number of competitors is 3:2. How many sixth grade students are there
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Q: the sixth grade of Guangming primary school held a calligraphy competition. The number of participants in the competition accounted for four seventh of the total number of students in the whole grade. Later, two students took part in the competition. At this time, the ratio of the number of participants to the number of non participants was 3:2. How many sixth grade students are there?
A: suppose there are X students in Grade 6 (and all the students who compete and are not compete are in Grade 6)
Then (4 / 7X + 2) / [(1-4 / 7) X-2] = 3 / 2
Solve the equation to get x = 70 (person)
This method is easy to understand, or 2 / (3 / 5-4 / 7) = 70 (person)

5 / 4 * 7.7 + 3.3 * 0.8-5 / 4 2x-1 and 2 / 2x = 5 / 4 / 2; 5 / 1 = 4 / 4; X

It seems to be three questions: 4 / 5 * 7.7 + 3.3 * 0.8-4 / 5
2x-1 and 1 / 2 x = 4 / 5
1 / 2:1 / 5 = 1 / 4: X
Question 1 = 0.8 * 7.7 + 3.3 * 0.8-0.8 = 0.8 * (7.7 + 3.3-1) = 0.8 * 10 = 8
Question 2: 2x-1.5x = 0.80.5x = 0.8 x = 1.6
Question 3: 0.5:0.2 = 0.25: x = 0.25 * 0.2 / 0.5 x = 0.1

On a square cardboard with a circumference of 80cm, cut out the largest circle. What is the circumference and area of the circle?
There is another way: a clock, the minute hand is 50 cm long, its tip turns 30 minutes, what is the distance?

On a square cardboard with a circumference of 80cm, cut out the largest circle. What is the circumference and area of the circle?
Perimeter 3.14 × 80 / 4 = 62.8 cm
Area: 3.14 × 80 / 8 × 80 / 8 = 314 square centimeters
A clock, the minute hand is 50 cm long, its tip turns 30 minutes, what's the distance?
3.14 × 50 × 2 × 30 / 60 = 157 cm

How much radiation does the high-speed railway with 350 km / h get when sitting on the train? How much radiation does the high-speed railway with 200 km / h get? What is the calculation formula?

Velocity has nothing to do with radiation. There is no formula

(x^2+3x+2)(x^2-9x+20)+9
Factorization

（x+1)(x+2)(x-4)(x-5)+9

Cut the largest circle on a square paper with a side length of 8 cm. The radius of the circle is______ Cm

Cut the biggest circle on the square paper, as shown in the figure below: so the diameter of the circle is the side length of the square, and the radius of the circle is 8 △ 2 = 4 (CM), so the answer is: 4

For example, v = s / T, speed = distance / time

Strength
1. Pressure: P = f / S
P is pressure, unit Pascal (PA) f is pressure, unit Newton (n) s is stressed area, unit square meter
2. Liquid pressure and buoyancy: F = 0
3. Density ρ = m / V
ρ is density, M is mass and V is volume
4. Gravity g = mg
5. Velocity v = s / T
6. Work w = fs (W for work, f for work)
7. Power P = w / T = FV
8. Mechanical efficiency η = w useful / W total = GH / Fs = g / FN (n is the number of strands of pulley block)
9. Thermal energy Q = cm △ t
10. Calorific value Q = MQ
11. Sliding friction f = (?) 181; n (F is sliding friction, n is positive pressure (?) 181; is friction coefficient and has no unit)
electric
1. Ohm's Law: I = u / R
2. Electric work: w = uit = Pt = I & # 178; RT = u & # 178 / RT (the latter two formulas are applicable to pure resistance circuit)
3. Electric power: P = UI = w / T = I & # 178; r = u & # 178 / R
Common data:
The speed of light in vacuum is 3 × 10 ^ 8 m / s
G 9.8 N / kg
Sound speed 340m / s in air at 15 ° C
The safety voltage is not higher than 36 v

If equation x ^ 2 + BX + 1 = 0 and equation x ^ 2-x-b = 0 have a common root, find B

x^2+bx+1=x^2-x-b
x(b+1)=-(b+1)
x=-1
b=2

Cut a cone-shaped paper cup for holding ice cream along the generatrix to get a circle with a radius of 20cm and a central angle of 216 degrees
Find the bottom radius and height of the paper cup

The arc length (L = n π R / 180) of the cone expansion is the circumference of the bottom surface of the cone,
The radius of the base of the cone (r = NR / 360) is the circumference of the base divided by 2 π
Cone height h = √ (generatrix & # 178; - cone bottom radius & # 178;)
therefore
The bottom radius of the paper cup is
r=216×20/360=12cm
The height of the paper cup is
h=√（20²-12²）=16cm