At what age do infants speak their first word of English? Here are 20 data of children (age in month XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX whAt is 99% confidence interval for the mean age at which children...

At what age do infants speak their first word of English? Here are 20 data of children (age in month) 15 26 10 9 15 20 18 11 8 20 7 9 10 11 11 10 12 17 11 10

whAt is 99% confidence interval for the mean age at which children speak first words? Upper limit?

lower limit?