Problems due thursday May 19

1. The Arizona Republic reported that the mean number of hours worked
per week by is 43.9.  The article further indicated that about one
third of those employed  work less than 40 hours per week.

a. Given this information and assuming that number of hours worked
follows the normal distribution, what is the standard deviation of the
number of hours worked?

b. What are the low and high number of hours worked per week that
represent 95% of the population of workers, according to the data? 
Assume a standard deviation of 4 hours per week for this calculation.

2.  Suppose 1.5 percent of the antennas on new Nokia cell phones are
defective.  For a random sample of 10 antennas, find the probability
that:

a.   None of the antennas is defective.
b.  Three or more of the antennas are defective.
c.   At most 3 are defective.
d.   All 10 antennas are defective.