In a class, the mean weight of 4 students is 90 kg and standard deviation is 30, then 95% confidence interval would be accordingly:
Here, Mean = 90 ; Standard deviation = 30
95% confidence interval = Mean +/- 2 S.D
Hence, 90+ (2x30) = 90+60 = 150
             90- (2x30) = 90-60 = 30
60-80
30-150
60-120
70-110