Question

. Crawling Data collected by child development scientists pro- duced this confidence interval for the average age (in weeks) at which babies begin to crawl: t-Interval for m 30.65 6 m(age) 6 32.89 (95.00% Confidence): a) Explain carefully what the software output means. b) What is the margin of error for this interval

Answer 1

Answer:

a) We can be 95% sure that true average age (in weeks) at which babies begin to crawl is between 30.65 weeks and 32.89 weeks.

b) Margin of error for the confidence interval is 1.12 weeks.

Step-by-step explanation:

Let m be the estimate of the average age (in weeks) at which babies begin to crawl

Let ME be the margin of error.

• Lower bound of the confidence interval is m-ME (32.89 weeks)
• Upper bound of the confidence interval is m+ME (30.65 weeks)

then the difference between the upper bound and the lower bound gives:

m+ME - (m-ME) = 2ME = 32.89-30.65=2.24 which gives

ME=1.12 weeks