Answer:
E(X) = 17.4
Step-by-step explanation:
We can calculate the expected value of a random X variable that is discrete (X takes specific values ) as:
E(X) = ∑xp(x) where x are the specific values of x and p(x) the probability associated with this x value.
In this way the expexted value is
E(X) = ∑xp(x) =(16*0.6)+(18*0.3)+(20*0.2) = 8+5.4+4 = 17.4
If the length, breadth and height of the box is denoted by a, b and h respectively, then V=a×b×h =32, and so h=32/ab. Now we have to maximize the surface area (lateral and the bottom) A = (2ah+2bh)+ab =2h(a+b)+ab = [64(a+b)/ab]+ab =64[(1/b)+(1/a)]+ab.
We treat A as a function of the variables and b and equating its partial derivatives with respect to a and b to 0. This gives {-64/(a^2)}+b=0, which means b=64/a^2. Since A(a,b) is symmetric in a and b, partial differentiation with respect to b gives a=64/b^2, ==>a=64[(a^2)/64}^2 =(a^4)/64. From this we get a=0 or a^3=64, which has the only real solution a=4. From the above relations or by symmetry, we get b=0 or b=4. For a=0 or b=0, the value of V is 0 and so are inadmissible. For a=4=b, we get h=32/ab =32/16 = 2.
Therefore the box has length and breadth as 4 ft each and a height of 2 ft.
Answer:
See proof below
Step-by-step explanation:
Given the expression 2/4-x = 10/4+x
Cross multiply
10(4-x) = 2(4+x)
10(4) - 10x = 2(4)+ 2x
40 - 10x = 8 + 2x
-10x - 2x = 8 - 40
-12x = -32
Multiply both sides by -1
-1(-12x) = -1(-32)
12x = 32
This shows the required expression
First you find the area of the front face 1/2bh or in you case 10x12=120 1/2 of 120 is 60 next you multiply 60 by 20 to get 1,200 for the voulume
Each one is multiplied by -2...
PROOF
-5 * 10 = -20
-20 * -2 = 40
And so on.
So we need two more numbers so do 40 * -2...
40 * -2 = -80
And then...
-80 * -2 = 160
So the first 6 numbers are...
-5, 10, -20, 40, -80, 160.
We need to find the SUM, which is all the numbers added together.
-5 + 10 - 20 + 40 - 80 + 160 = 105
105 is your answer.
