aima

a. An independent random sample of 50 and 70 animals from two farmsshow the average animal weight to be 50 kg and 40 kg with standard deviation of 2.5 kg and 1.5 kg respectively. Assuming normality, construct a 95% confidence interval for the expected dif...

The standard deviation of the lifetime of certain TV picture tubes is estimated as 150 hours. How much large a sample must be taken in order to be 99% confident that the error in the estimated means lifetime will not exceed 25 hours