Answer:
The probability that the sample proportion is between 0.35 and 0.5 is 0.7895
Step-by-step explanation:
To calculate the probability that the sample proportion is between 0.35 and 0.5 we need to know the z-scores of the sample proportions 0.35 and 0.5.
z-score of the sample proportion is calculated as
z= where
- p(s) is the sample proportion of first time customers
- p is the proportion of first time customers based on historical data
- N is the sample size
For the sample proportion 0.35:
z(0.35)= ≈ -1.035
For the sample proportion 0.5:
z(0.5)= ≈ 1.553
The probabilities for z of being smaller than these z-scores are:
P(z<z(0.35))= 0.1503
P(z<z(0.5))= 0.9398
Then the probability that the sample proportion is between 0.35 and 0.5 is
P(z(0.35)<z<z(0.5))= 0.9398 - 0.1503 =0.7895