Question

2. Arsenic is a compound that occurs naturally in very low concentrations. Arsenic blood concentrations in healthy individuals are Normally distributed, with a mean of 3.2 mg/dl and a standard deviation of 1.5 mg/dl. A researcher believes that one area of the United States has naturally elevated arsenic levels in the ground and water supplies. An SRS of 25 individuals in this area found a sample mean arsenic level of 3.75 mg/dl. What are the null and alternative hypotheses for this study?

Answer 1

Answer:

The null hypothesis                 $H_o : \mu = 3.2 \ mg/dl$

The alternative hypothesis      $H_a : \mu > 3.2 \ mg/dl$

Step-by-step explanation:

From the question we are told that

  The mean is  $\mu = 3.2 \ mg/dl$

   The standard deviation is $\sigma = 1.5 mg/dl$

   The sample size is  n = 25

    The sample mean is  $\= x = 3.75 \ mg /dl$

Generally

   The null hypothesis is : That the mean of the  Arsenic blood concentrations in healthy individuals is $\mu = 3.2 \ mg/dl$

i.e

The null hypothesis  $H_o : \mu = 3.2 \ mg/dl$

    The alternative hypothesis is : That the mean of the  Arsenic blood concentrations in healthy individuals is greater than  $\mu = 3.2 \ mg/dl$

The alternative hypothesis      $H_a : \mu > 3.2 \ mg/dl$