4. (10pts) Suppose that 40% of U.S. voters are Democrats. What is the probability that in a sample of 200 voters that at least 90 people will be Democrat?
P[ voters are Democrat ] = 40% = 0.4
Sample size = n = 200
P[ At least 90 ] = P[ X > 90 ] = P[ p > 90/200 ] = P[ p > 0.45 ]
The following information has been provided about the population proportion and the sample size:
Population Proportion = | 0.4 |
Sample Size = | 200 |
We need to compute . Based on the information provided, the population men of sample proportions and the corresponding standard error are:
Now, the following is obtained using normal approximation:
Get Answers For Free
Most questions answered within 1 hours.