Homework #3

Due Tuesday February 8.
 
1. Create a spreadsheet that simulates customer arrival times at a store where 10 customers arrive on average per hour; generate several dozen arrival times.  (Use the exponential distribution with Mean equal to 10.0 to create the required Poisson process.)
2. Compute the mean, variance and standard deviation of the given numbers:  (Fill in the table.) 
numbers differences differences squared
7 X X
9 X X
3 X X
12 X X
8 X X
total XXXXXX total
mean variance
standard deviation XXXXXX
 
3. The spreadsheet HomeData.xls gives home prices for two different communities.  For each community, compute the mean, median and standard deviation of the home prices.  Also plot histograms for each community.
4. A biologist determines that weights of starfish in a certain lagoon are normally distributed with mean 2.3 kg and standard deviation 0.4 kg.  What is the probability that the weight of a randomly selected starfish is less than 2.5 kg?  Use the Excel function NORMDIST to compute the answer.
5. The Stanford-Binet IQ test is supposed to have mean 100 and standard deviation 15.  Assuming that the IQs are normally distributed, what is the probability that a randomly selected person has IQ between 100 and 105?  Use the Excel function NORMDIST to find the probability.  Also, give the z-score of 100 and the z-score of 105.