Posted by miriam on Thursday, March 31, 2011 at 12:40am.
Find mean and standard deviation. Use z-scores to find z, then a z-table to find your probability based on the z-score. This is a normal approximation to the binomial distribution.
I'll get you started:
mean = np = (500)(.56) = ?
standard deviation = √npq = √(500)(.56)(.44) = ?
Note: q = 1 - p
Finish the calculations.
To find z-score:
z = (x - mean)/sd
Note: x = 250
Once you have the z-score, look in a z-table using the score to find your probability. Remember that the question is asking "at least 250" when looking at the table.
.243
Related Questions
statistics - Of all 3- to 5-year old children, 56% are enrolled in school (p=0....
Math urgent..............help..... - the table below shows the registered ...
Statistics - According to a 2000 study by the Bureau of Justice Statistics, ...
elementary statistics - 56% of families had no children under the age of 18;17% ...
statistics - Suppose you sample randomly, without replacement, a number between ...
PROB - Researchers at the University of Pennsylvania School of Medicine have ...
ap statistics - an opinion poll asks a sample of 500 adults (an SRS) whether ...
Statistics - A simple random sample of 50 female 14-year-olds is selected. The ...
probabilityv - A school's administrators are concerned about absenteeism at ...
Statistics - An educator wants to estimate the proportion of school children in ...
For Further Reading
