The maximum water nitrite level allowed is 0.5 mg-L'l. Dr. TheIrien wants to know the number of water samples needed to declare with a probability of 0.9 that there is an excess in nitrite level (OL = 0.01) when the population mean is 0.1 mg-L'1 above the maximum allowed. The population variance is assumed to be known and equal to 0.04 (mg-L'1)2