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A stock calculation problem I bought 1000 shares of a stock at 20.5 yuan. When the share price was 17.1 yuan, I bought 1000 shares again. Then I sold 1000 shares at 17.3 yuan?
A lot of methods, generally average, is the second time to buy together
(20.5 + 17.1) * 1000 / 2000 = 18.8 yuan / share, and then sell 1000 shares, which means you sell 17.3 * 1000 yuan, minus the cost of 18.8 * 1000, then your current stock cost is 1000 * 18.1~
Common formulas of middle school mathematics practical problems
More details. Thank you
Distance = speed * time
Encounter distance = (speed and) * encounter time
Overtaking distance = speed difference * overtaking time
Workload = work efficiency * work time
Velocity along water (wind) = velocity of object itself + velocity of water (wind)
When solving practical problems, we should pay attention to the key sentence, that is, the equality relation of the problem
Common formulas of applied mathematics problems in primary and secondary schools
1. Number of copies × number of copies = total number
Total number of copies
Total number of copies = number of copies
2.1 times × times = several times
How many times △ 1 times = Times
Several times △ times = 1 times
3 speed × time = distance
Distance △ speed = time
Distance △ time = speed
4 unit price × quantity = total price
Total price / unit price = quantity
Total price △ quantity = unit price
5. Working efficiency × working time = total amount of work
Total workload △ work efficiency = working hours
Total amount of work △ working time = working efficiency
6 addend + addend = sum
Sum - one addend = another addend
7 subtracted - subtracted = difference
Subtracted difference = subtracted
Difference + subtraction = subtracted
8 factor × factor = product
Product △ one factor = another factor
9 divisor / divisor = quotient
Divisor / quotient = divisor
Quotient x divisor = divisor
Primary school mathematics figure calculation formula
1 square
C perimeter s area a side length
Perimeter = side length × 4
C=4a
Area = side length × side length
S=a×a
2 cube
5: Volume a: edge length
Surface area = edge length × edge length × 6
S table = a × a × 6
Volume = edge length × edge length × edge length
V=a×a×a
3 rectangle
C perimeter s area a side length
Perimeter = (length + width) × 2
C=2(a+b)
Area = length × width
S=ab
4 cuboid
5: Volume s: Area A: length B: width H: height
(1) Surface area (L × W + L × H + W × h) × 2
S=2(ab+ah+bh)
(2) Volume = length × width × height
V=abh
5 triangles
S area a bottom h height
Area = bottom × height △ 2
s=ah÷2
Triangle height = area × 2 △ bottom
Triangle bottom = area × 2 △ height
6 parallelogram
S area a bottom h height
Area = bottom × height
s=ah
7 trapezoid
S area a upper bottom B lower bottom h height
Area = (upper bottom + lower bottom) × height △ 2
s=(a+b)× h÷2
8 round
S area C perimeter Π d = diameter r = radius
(1) Perimeter = diameter ×Π = 2 ×Π× radius
C=∏d=2∏r
(2) Area = radius × radius ×Π
9 cylinder
v: Volume H: height s; bottom area R: bottom radius C: bottom perimeter
(1) Side area = perimeter of bottom surface × height
(2) Surface area = side area + bottom area × 2
(3) Volume = bottom area × height
(4) Volume = side area △ 2 × radius
10 cone
v: Volume H: height s; bottom area R: bottom radius
Volume = bottom area × height △ 3
Total number △ total number of copies = average number
The formula of sum difference problem
(sum + difference) △ 2 = large number
(sum difference) △ 2 = decimal
The problem of sum times
Sum (multiple-1) = decimal
Decimals × multiples = large numbers
(or sum - decimal = large)
Differential multiple problem
Difference (multiple-1) = decimal
Decimals × multiples = large numbers
(or decimal + difference = large)
The problem of tree planting
1. The tree planting problem on non closed lines can be divided into the following three cases
(1) if trees are to be planted at both ends of the non closed line, then:
Number of plants = number of segments + 1 = total length △ plant spacing-1
Total length = plant spacing × (number of plants - 1)
Plant spacing = total length (number of plants - 1)
(2) if trees are to be planted at one end of the non closed line and not at the other end, then:
Number of plants = number of segments = total length △ plant spacing
Total length = plant spacing × number of plants
Plant spacing = total length △ number of plants
(3) if trees are not planted at both ends of the non closed line, then:
Number of plants = number of segments-1 = total length △ spacing-1
Total length = plant spacing × (number of plants + 1)
Plant spacing = total length (number of plants + 1)
2. The quantitative relationship of tree planting on closed lines is as follows
Number of plants = number of segments = total length △ plant spacing
Total length = plant spacing × number of plants
Plant spacing = total length △ number of plants
Profit and loss
(profit + loss) △ the difference between the two distributions = the number of shares participating in the distribution
(big profit - small profit) △ the difference between the two distributions = the number of shares participating in the distribution
(big loss - small loss) △ the difference between the two distributions = the number of shares participating in the distribution
Encounter problem
Encounter distance = speed and X encounter time
Encounter time = encounter distance △ speed and
Speed sum = encounter distance △ encounter time
Follow up questions
Pursuit distance = speed difference × pursuit time
Pursuit time = pursuit distance △ speed difference
Speed difference = pursuit distance △ pursuit time
Flow problem
Downstream velocity = hydrostatic velocity + water velocity
Countercurrent velocity = still water velocity - water velocity
Hydrostatic velocity = (downstream velocity + countercurrent velocity) △ 2
Water flow velocity = (downstream velocity countercurrent velocity) △ 2
Concentration problem
Weight of solute + weight of solvent = weight of solution
Weight of solute / weight of solution × 100% = concentration
Weight of solution × concentration = weight of solute
Weight of solute △ concentration = weight of solution
Profit and discount
Profit = selling price cost
Profit margin = profit / cost × 100% = (selling price / cost-1) × 100%
Up and down amount = principal × up and down percentage
Discount = actual selling price △ original selling price × 100% (discount < 1)
Interest = principal × interest rate × time
After tax interest = principal × interest rate × time × (1-20%)
Hydrogen in alcohol solution accounts for 12%, and the mass fraction of solute is calculated
Let the mass fraction be X
In water, hydrogen mass ratio is 2 / 18
In ethanol, the mass ratio of hydrogen is 6 / 46
In solution
6/46*x+2/18*（1-x）=12%
x=0.46
46% by mass
What is the result of simplifying M-N / M-N / n square?
m^2/m-n-n^2/m-n =(m^2-n^2)/m-n =(m+n)(m-n)/m-n =m+n
(1) 3 / 11 + 5.13 + 8 / 11 + 0.87 (2) 7.6 × 3 / 5 + 7.6 × 0.4
3/11+5.13+8/11+0.87
=3/11+8/11+（5.13+0.87）
=1+6
=7
7.6×3/5+7.6×0.4
=7.6x（3/5+0.4）
=7.6x（0.6+0.4）
=7.6
I wish you progress in your study_ O ha!
If it can help you, I hope to adopt o (∩)_ O ha!
If you still don't understand, you can continue to ask (^ o ^)/~
1. (9 / 10 - 4 / 5 × 5 / 8) divided by 5 / 8, can it be calculated simply
2. To process a batch of parts, Party A and Party B can cooperate for 20 days. Now, Party A will do it for 16 days first, and then Party B will do it for 12 days, which is exactly 11 / 15 of this batch of parts. How many days will it take for Party B to complete it alone
Question 1: (9 / 10-4 / 5 * 5 / 8) △ 5 / 8 = 9 / 10 △ 5 / 8-4 / 5 * 5 / 8 △ 5 / 8 = 36 / 25-4 / 5 = 16 / 25
Ask Party A and Party B to work together for 12 days: 12 * 1 / 20 = 3 / 5
2. The workload of Party A is 16 days, 16-12 = 4 days: 11 / 15-3 / 5 = 2 / 15
3. Work efficiency of Party A: 2 / 15 △ 4 = 1 / 30
4. The number of days for Party B to complete alone: 1 △ 1 / 20-1 / 30 = 1 △ 1 / 60 = 60 (days)
1 / 4 * 2003 + 2005 *% 25 + 2004 * 1 / 4 (simple calculation)
1 / 4 * 2003 + 2005 *% 25 + 2004 * 1 / 4
= 1/4×（2003 + 2005+ 2004）
= 1/4×6012
= 1503
Simple calculation law
25 * 4.4 = 25 * 4 * 1.1 applies () multiplication law
Law of Association
724-324-76-24 calculated by simple method
724-324-76-24
=(724-324)-(76+24)
=400-100
=300
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