Answer:
A. E(x) = 1/n×n(n+1)/2
B. E(x²) = 1/n
Step-by-step explanation:
The n candidates for a job have been ranked 1,2,3....n. Let x be the rank of a randomly selected candidate. Therefore, the PMF of X is given as
P(x) = {1/n, x = 1,2...n}
Therefore,
Expectation of X
E(x) = summation {xP(×)}
= summation {X×1/n}
= 1/n summation{x}
= 1/n×n(n+1)/2
= n+1/2
Thus, E(x) = 1/n×n(n+1)/2
Value of E(x²)
E(x²) = summation {x²P(×)}
= summation{x²×1/n}
= 1/n
Well, if he sold 17 of them for $18, 17 times 18 = $306. Now he has 31 backpacks left. 31 times 25 = $775. 775 + 306= $1081 (final answer) Hope it helps!!!
Please write x^2, not x2.
If you stretch the graph of y=x^2 vertically by a factor of 4, the resulting graph represents the quadratic function y = 4x^2. It's still a parabola, but appears to be thinner.
This particular question is about horizontal stretching, however. Stretching the graph horizontally by a factor of 4 results in the new function g(x) = (x/4)^2. Try graphing x^2 and also (x/4)^2 on the same set of axes to observe this phenomenon.
Answer: 9
Step-by-step explanation:
If Jack can paint the room in 9 hours by his self she can only do the same
