Hello, thank you for taking the time to post your question!
the general form that you want to use here to compute the confidence interval of a proportion is
p-hat +/- (z* (sqrt(p-hat * (1 – p-hat) / n)))
from the information given in the table we know that
p-hat = 40/100 = 0.40
n = 100
then for the 95% level of confidence it would be z* = 1.96
putting that all together and simplifying should make the 95% confidence interval here
0.40 +/- 0.096
=0.304 to 0.496
that means that we can be 95% confident that the true proportion of left-handed individuals in the entire population lies between 30.4% and 49.6%!
I hope that helps get you moving in the right direction! Feel free to reach out if you have any additional questions beyond that :)
