Need to use Z (normal) distribution not Bi-Nomial.
A March 13, 2010 Wall Street Journal article reported that, to the dismay of Microsoft management, approximately 10% of Microsoft employees were iPhone users. Of course, iPhones are a product of Apple, Inc., Microsoft’s biggest competitor. The following is an excerpt from the article, titled “Forbidden Fruit: Microsoft Workers Hide Their iPhones” ( http://online.wsj.com/article/SB10001424052748703455804575057651922457356.html ) which highlighted the risk of being an iPhone user at a Microsoft function in September, 2009.
“At an all- company meeting in a Seattle sports stadium, one hapless employee used his iPhone to snap photos of Microsoft Chief Executive Steve Ballmer. Mr. Ballmer snatched the iPhone out of the employee's hands, placed it on the ground and pretended to stomp on it in front of thousands of Microsoft workers, according to people present.”
Suppose sixty Microsoft employees are randomly selected. Use the normal approximation to the binomial distribution to determine the probability that:
- a) Less than 5 employees are iPhone users
- b) Exactly 6, 7, 8 or 9 employees are iPhone users
- c) 9 or more employees are iPhone users
****HINT – Since the mean (mu) and standard deviation are not given, you will have to calculate the mean and standard deviation. Mean of a Binomial Distribution Formula & Variance of Binomial Distribution (page 173)*****