Mean = np = 517 * .076 = 39.292
Standard deviation = √npq = √(517 * .076 * .924) = √(36.3058) = 6.025
Note: q = 1 - p
x = .08 * 517 = 41.36
Use z-scores:
z = (x - mean)/sd
Therefore:
z = (41.36 - 39.292)/(6.025) = 0.34
Check a z-table for the probability using the z-score calculated above. Remember that the problem is asking "less than" when looking at the table.
I hope this helps.
Suppose that 7.6% of all people are allergic to the H1N1 vaccine. A sample of 517 people are selected
a. Calculate the probability that less than 8% of the sample will be allergic to vaccine.
1 answer
1 answer