Problem 19.23: Vitamin D, whether ingested as a dietary supplement or produced
naturally when the skin is exposed to sunlight, is essential for strong, healthy bones.
The bone disease rickets was largely eliminated in England during the 1950’s, but
now there is concern that a generation of children more likely to watch television or
play computer games than spend time outdoors is at increased risk. A recent study
of 2700 children randomly selected from all parts of England found 20% of them
deficient in Vitamin D.
a) Find a 98% confidence interval.
b) Explain carefully what your interval means.
c) Explain what “98% confidence” means.
Problem 19.24: In 1998, a San Diego reproductive clinic reported 49 live births to
207 women under the age of 40 who had previously been unable to conceive.
a) Find a 90% confidence interval for the success rate at this clinic.
b) Interpret your interval in this context.
c) Explain what “90% confidence” means.
d) Do these data refute the clinic’s claim of a 25% success rate? Explain.
Problem 20.17: According to the Law School Admission Council, in the fall of 2006,
63% of law school applicants were accepted by some law school? The