this may help you
it is given that the standard deviation 0.8, so we can use the normal distribution critical value for the 95% confidence interval.
sample mean = 2.36
standard deviation = 0.8
standard error of mean = σ / √ n
standard error of mean = 0.8 / √ 50
se = 0.8/7.0711
standard error of mean 0.1131
Confidence interval 2.36-(0.1131)(1.96)
and 2.36+(0.1131)(1.96)
95% confidence interval :(2.14, 2.58)
