Answer:
852 students walking to school
Step-by-step explanation:
Lets start with a simple example so you can get it
if 60% of 100 students walk to school that means
60 students walk to school... right??
so lets simplify it more that means you have multiplied 100 (students) by 60%
or (note: you can say that 60% is equal to
)
so the problem told 60% of 1420 students walk to school that means we should
do this:
Answer:
a) To determine the minimum sample size we need to use the formula shown in the picture 1.
E is the margin of error, which is the distance from the limits to the middle (the mean) of the confidence interval. This means that we have to divide the range of the interval by 2 to find this distance.
E = 0.5/2 = 0.25
Now we apply the formula
n = (1.645*0.80/0.25)^2 = 27.7 = 28
The minimum sample size would be 28.
b) To answer the question we are going to make a 90% confidence interval. The formula is:
(μ - E, μ + E)
μ is the mean which is 127. The formula for E is shown in the picture.
E = 0.80*1.645/√8 = 0.47
(126.5, 127.5)
This means that the true mean is going to be contained in this interval 90% of the time. This is why it doesn't seem possible that the population mean is exactly 128.
