Unfortunately, arsenic occurs naturally in some ground water.+ A mean arsenic level of / = 8.0 parts per billion (ppb) is considered safe for agricultural use. A well In Texas is used to water cotton crops. This well is tested on a regular basis for arsenic. A random sample of 36 tests gave a sample mean of x = 6.7 ppb arsenic, with s = 3.0 ppb. Does this information indicate that the mean level of arsenic in this well is less than 8 ppb? Use a = 0.01. In USE SALT (a) What is the level of significance? State the null and alternate hypotheses. O Ho: H = 8 ppb; Hi: u 8 ppb; Hi: H = 8 ppb O Hoil = 8 ppb; H, : H > 8 ppb O Ho: H