Answer: 
Step-by-step explanation:
The confidence interval for population mean is given by :-

Given : Sample size :
, which is a large sample , so we apply z-test .
Sample mean : 
Standard deviation : 
Significance level : 
Critical value : 
Now, a confidence interval at the 95% level of confidence will be :-

Answer: A≈440.44
Step-by-step explanation:
Answer:
3.6 gB
Step-by-step explanation:
You can think of this question in terms of the y = mx+b equation.
$78.90 is y because it is the total amount per month, $4 is m because it is the cost per gB, and $64.50 is b because it is the flat rate.
78.9 = 4x + 64.5
4x = 14.4
x = 3.6 gB of data (or 3 if it wants a whole number)
Step-by-step explanation:
3cm on map = 45 km
1 cm on map = Xkm
Xkm = 45 / 3
Xkm = 15km
Therefore scale = 1:15000