Question

1. Vitamin​ D, whether ingested as a dietary supplement or produced naturally when sunlight falls upon the​ skin, is essential for​ strong, healthy bones. The bone disease rickets was largely eliminated during the​ 1950s, but now there is concern that a generation of children more likely to watch TV or play computer games than spend time outdoors is at increased risk. A recent study of 2400 children randomly selected found 23​% of them deficient in vitamin D.

a) Construct a​ 98% confidence interval for the true proportion of children who are deficient in vitamin D.

2. A 2011 poll found that 76​% of citizens of a certain country believe that high achieving high school students should be recruited to become teachers. This poll was based on a random sample of 1003 citizens.

​a) Find a​ 90% confidence interval for the proportion of citizens who would agree with this.

Answer 1