You are told that in a sample of size 225 the mean is 48.5 and the standard deviation is 1.8. The study is reported with 90% con
2 answers:
You might be interested in
Answer:
There is a 2.28% probability that it takes less than one minute to find a parking space. Since this probability is smaller than 5%, you would be surprised to find a parking space so fast.
Step-by-step explanation:
Problems of normally distributed samples can be solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by
After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X.
Also, a probability is unusual if it is lesser than 5%. If it is unusual, it is surprising.
In this problem:
The length of time it takes to find a parking space at 9 A.M. follows a normal distribution with a mean of 7 minutes and a standard deviation of 3 minutes, so .
We need to find the probability that it takes less than one minute to find a parking space.
So we need to find the pvalue of Z when
has a pvalue of 0.0228.
There is a 2.28% probability that it takes less than one minute to find a parking space. Since this probability is smaller than 5%, you would be surprised to find a parking space so fast.