(a) The standard error of the mean (SEM) for the U.S. babies is 0.083.
(b) An approximate 95% confidence interval for the mean sleep time for 6-month-old babies in the United States is 12.8367< μ1< 13.163.
(c) An approximate 95% for the difference in average sleep time for 6-month-old Dutch and U.S. infants is −2.203< μ1 <μ2 < −1.7969.
What is standard error and how it is measured?
A statistical concept known as the standard error uses standard deviation to assess how accurately a sample distribution represents a population. The standard error of the mean describes the statistical variation between a sample mean and the population's actual mean.
According to the given information:
In United States:
Sample size 
Mean, 
Standard deviation, 
In Netherlands:
Sample size, 
Mean, 
Standard deviation, 
(a) For the newborns in the United States, the standard error of the mean (SEM) is determined as follows:

(b) The following formula is used to determine the 95% confidence interval for the mean sleep time for babies aged 6 months in the United States:


(c) The 95% difference in the amount of time newborns in the Netherlands and the United States spend sleeping on average is computed as follows:

To know more about standard error:
brainly.com/question/29363195
#SPJ4