Answer:
The confidence interval is ( 0.225952516, 0.474047484)
People will get different results because, the amount of sedans may be dependent on the area in which the data is taken.
No, the sample is not really a good representation of the whole population of vehicles, since only a certain area was sampled or experimented.
Step-by-step explanation:
Solution
Given that:
From the experiment we discovered that out of 40 vehicles, 14 of them were sedans.
Let us note that:
p^ = It is the point estimate of the population proportion
Where,
n=/n = 0.35
We also check for the standard error of p, sp:
which is,
sp =√{p^ (1-p^)/n] =0.075415516
Thus,
for the the critical z, we have the following:
α/2 = 0.05
So,
z (α)/2 = 1.644853627
Thus,
For lower bound = p^ - z(α/2) * sp = 0.225952516
For upper bound = p^ + z(α/2)* sp = 0.474047484
Hence,
The confidence interval becomes: ( 0.225952516, 0.474047484)
