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
Answer:
Mean age = 1271.27
Step-by-step explanation:
No of children = 77
The age at which children first began to combine words = 16.51 months
Mean age = No of children × age at which children first began to combine words
= 77 × 16.51
= 1271.27
Mean age = 1271.27
Think of imaginary numbers on a complex plane as coordinates - take the real part, that's the x coordinate, the imaginary part that's the y coordinate.
Therefore, for the first blank, -1+3i lies in the shaded area, because its coordinates are (-1,3).
And following on from that for the second one, -4i does not lie in the shaded area, since its coordinates are (0,-4).
Tl;dr is taking a complex number a+bi and placing it on a complex plane, it will have coordinates (a,b)
So average=(total of scores)/(number of tests)
needs at least average of 70
at least is represented as greater than or equal to or the sign (<u>></u>)
70<u>></u>(total)/(number oftests)
since we have 3 tests, we have to have 3 scores so
70<u>></u>(x+y+z)/3
he scored 85 and 60
70<u>></u>(x+85+60)/3 (doesn't matter which to subsitute)
70<u>></u>(x+145)/3
multiply obht sides by 3
210<u>></u>x+145
subtract 145 from both sides
65<u>></u>x
he needs to get at leas 65 on his third test
Yes the mean is the middle number so go according to the order from smallest to biggest 48 is the middle number
