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# Poisson & Standard Normal Probabilities

1) A survey of citizens over 60 years old who have too much money to qualify for medicaid, but have no health insurance. The ages of the 25 uninsured citizens are:
60 61 62 63 64 65 66 68 68 69 70 73 73
74 75 76 76 81 81 82 86 87 89 90 92

We know that 1/4 of the citizens are below 65.5 years of age.

a. What type of shape does the distribution of the sample appear to have?
b. Calculate the standard deviation of the ages of the uninsured citizens correct to the nearest hundredth of a year.
c. Calculate the coefficient of variation of the ages of the citizens.

2) Suppose Z has a standardized normal distribution with a mean of 0 and a standard deviation of 1. The probability that Z values are larger than______ is 0.6985.

3) Suppose Z has a standardized normal distribution with a mean of 0 and a standard deviation of 1. So, 96% of the possible Z values are between______and________. (symmetrically distributed about the mean)
The answer is -2.05 and 2.05 or -2.06 and 2.06