Assuming you meant her sister used 200 minutes which im still a little unclear of
if everyone in the family used 350 minutes it would add up to 1400, this is the number you want your minutes to add up to
400
350
200 thats 950
subtract 950 from 1400 and you have 450
450 Minutes is your answer
Answer:
u = 4.604 , s = 2.903
u' = 23.025 , s' = 6.49
Step-by-step explanation:
Solution:
- We will use the distribution to calculate mean and standard deviation of random variable X.
- Mean = u = E ( X ) = Sum ( X*p(x) )
u = 1*0.229 + 2*0.113 + 3*0.114 + 4*0.076 + 5*0.052 + 6*0.027 + 7*0.031 + 8*0.358.
u = 4.604
- Standard deviation s = sqrt ( Var ( X ) = sqrt ( E ( X^2) + [E(X)]^2
s = sqrt [ 1*0.229 + 4*0.113 + 9*0.114 + 16*0.076 + 25*0.052 + 36*0.027 + 49*0.031 + 64*0.358 - 4.604^2 ]
s = sqrt ( 8.429184 )
s = 2.903
- We will use properties of E ( X ) and Var ( X ) as follows:
- Mean = u' = E (Rate*X) = Rate*E(X) = $5*u =
u' = $5*4.605
u' = 23.025
- standard deviation = s' = sqrt (Var (Rate*X) ) = sqrt(Rate)*sqrt(Var(X)) = sqrt($5)*s =
s' = sqrt($5)*2.903
u' = 6.49
Answer:
Between (-0.675, 0.675)
Step-by-step explanation:
We know that a standard normal distribution curve is bell shaped unimodal , symmetrical about mean.
for thsi standard normal variate with notation z, we get mean =0 and std deviation = 1
For the middle shaded region, we find z such that the area between -z and z is 0.50 exactly half.
From standard normal distribution table, we get that z= ±0.675
Hence between z=-0.675 and z = 0.675 we get the middle region with area equal to exactly 1/2.
Between (-0.675, 0.675)