We need to find out how many adults must the brand manager survey in order to be 90% confident that his estimate is within five percentage points of the true population percentage.
From the given data we know that our confidence level is 90%. From Standard Normal Table we know that the critical level at 90% confidence level is 1.645. In other words, 
.
We also know that E=5% or E=0.05
Also, since, 
is not given, we will assume that =0.5. This is because, the formula that we use will have 
in the expression and that will be maximum only when =0.5. (For any other value of , we will get a value less than 0.25. For example if, is 0.4, then 
and thus, 
.).
We will now use the formula
We will now substitute all the data that we have and we will get
which can approximated to n=271.
So, the brand manager needs a sample size of 271
your question is not really a question.
Answer:
A
Step-by-step explanation:
Because this ia so simple I don't even need to explain to waste my last few brain cells.
Answer: b) The data is spread close to the mean
Step-by-step explanation: Theoretically, when the standard deviation of a statistical data is large or high, it simply means that the values in such statistical data set are farther away from the mean, On the other hand when the standard deviation is small or low, it simply means that the values of such statistical data are close to the mean of those data on average.
Therefore Judy's low standard deviation for her project simply indicates that her statistical data set is spread close to the mean.
She is incorrect, the product will have 3 decimal places.
