Answer to Question #300491 in Statistics and Probability for Tzuyu

Question

In 2012 the Centers for Disease Control and Prevention reported that the rate of autism in children has risen to in 50. A study conducted in Norway suggests that the risk of autism may be significantly lower if women take folic acid supplements during pregnancy. Suppose a large medical center enlists 900 expectant mothers in a trial; the women agree to take the folic acid for the duration of their pregnancies. The researchers will track the children after birth to see how many develop autism.

c) If folic acid supplements actually have no effect, what is the probability that more than 25 children have autism?

d) How low would the number of autism cases among these 900 children have to be in order to convince you that the folic acid supplements may be effective (statistically significant)? Explain your reasoning. Show statistical calculations to support your reasoning.