probability question

[asfer]

Suppose that 45 percent of the Americans favor Donald Trump in upcoming election in November. A survey conducted on a random sample of size 200 voters, find the approximate probability that more than half the members of the sample favor Donald Trump.

can anyone help me in this I am confused if I convert 200(0.45)=90 and then solve or is there any formuls

 

[Prof]

This is a binomial problem with a large enough sample that you can approximate it with a normal distribution. You have correctly found the mean of the normal distribution, 90 (the most likely result in a sample of 200). Then figure out the standard deviation with a formula for proportions. Then find the probability of getting more than half of 200 for this normal distribution with a calculator or computer or table (however you do it in class). I do it with normalcdf on a TI-83 calculator.