Reference no: EM132483482

1. An industrial designer wants to determine the average amount of time it takes an adult to assemble an "easy to assemble" toy. A sample of 16 times yielded an average time of 19.9 minutes, with a sample standard deviation of 6 minutes. Assuming normality of assembly times, provide a 90% confidence interval for the mean assembly time.

2. Data collected by child development scientists produced the following 90% confidence interval for the average age (in months) at which children say their first word: (10.1 months, 13.4 months). Which statement correctly interprets this interval?

a) Based on this sample, we can say, with 90% confidence, that the mean age at which children say their first word is between 10.1 and 13.4 months.

b) 90% of the children in this sample said their first word when they were between 10.1 and 13.4 months old.

c) If we took many random samples of children, about 90% of them would produce this confidence interval.

d) We are 90% sure that a child will say his first word when he is between 10.1 and 13.4 months old.