Question 1076071
The standard error is sigma/sqrt(n)=200/sqrt(50)=28.3 l
The 95% CI is mean +/- 1.96*SE; we don't use the t here, because we are given the sd of the population.
That is mean +/- (1.96*28.3)=500+/-55.4 liters or (444.6, 555.4)