Answer:
Confidence interval: (0.04649,0.04913)
Step-by-step explanation:
We are given the following in the question:
Sample size, n = 100,000
Number of people who donated, x = 4781
95% Confidence interval:
Putting the values, we get:
is the required 95% confidence interval for the true proportion of their entire mailing list who may donate.
Answer:
And we can find this probability using the complement rule and with the normal standard table or excel:
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the average household spent of a population, and for this case we know the distribution for X is given by:
Where and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability using the complement rule and with the normal standard table or excel: