Answer:
So the answer for this case would be n=220 rounded up to the nearest integer
Step-by-step explanation:
Information given
represent the population deviation
represent the margin of error
The margin of error for the true mean is given by this formula:
(a)
And on this case we have that ME =5 and we are interested in order to find the value of n, if we solve n from equation (4) we got:
(b)
The critical value for 90% of confidence interval now can be founded using the normal distribution. The significance level is 
and the critical value would be 
, replacing into formula (b) we got:
So the answer for this case would be n=220 rounded up to the nearest integer
Answer:
Yes.
Step-by-step explanation:
Step-by-step explanation:
Distance = rate × time
If B is the rate of the boat, and C is the rate of the current, then we can write two equations:
18 = (B + C) × 3
18 = (B − C) × 9
Simplifying the equations:
6 = B + C
2 = B − C
Add the equations together to eliminate C:
8 = 2B
B = 4
Plug into either equation to find C:
C = 2
The boat's rate is 4 mph, and the current's rate is 2 mph.
-9.5 because 5-9.5=-4.5 and -4.5+9.5=5. So yeah 5-9.5=5+-9.5 ?
