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
The lengths of the rectangles are 7 and 12 respectively. Form the ratio 7/12. The widths of the rects. are x and 5 respectively. Form the ratio x/5. Now equate these two ratios:
7 x
--- = ---
12 5
Solve this for x. One way to do this would be to cross-multiply, obtaining 12x = 35, and solving this result for x. x will be a fraction. Write the numerator and denominator in the boxes given.
Answer:
y = 460 miles per hr
x = 500 miles per hr
Step-by-step explanation:
Let the planes be X any
Let their speeds be xmiles/hr and ymiles/hr respectively
x = y + 40 (assuming X is faster by 40miles/hr)
Distance travelled by X to meet Y = 0.75x
Distance travelled by Y to meet X = 0.75y
0.75x + 0.75y = 720 --------1
Put x = y + 40 in eqn 1
0.75(y+40) + 0.75y = 720
0.75y + 30 + 0.75y= 720
1.5y = 690
y = 460 miles per hr
x = 460 +40
= 500 miles per hr
The input of each of these functions is always an angle, and as you learned in the previous sections, these angles can take on any real number value. Therefore the sine and cosine function have the same domain, the set of all real numbers, \begin{align*}R\end{align*}
Answer:
300
Step-by-step explanation:
