in-20122012-the-mean-zinc-concentration-in-a-lake-was-reported-as-00350035-mglte

Question

In $2012$ , the mean zinc concentration in a lake was reported as $0.035$ $mg/L$ . In $2021$ , a random sample of $9$ measurements yielded: $0.032$ , $0.034$ , $0.036$ , $0.033$ , $0.035$ , $0.037$ , $0.034$ , $0.036$ , $0.033$ $mg/L$ . Assume normality and no outliers. At the $alpha equals 0.05$ significance level, is there evidence that the mean zinc concentration has changed since $2012$ ?

Accepted Answer

There is insufficient evidence to conclude that the mean zinc concentration has changed since $2012$

Answer

There is sufficient evidence to conclude that the mean zinc concentration has changed since $2012$

Answer

The sample mean equals the historical mean, so no test is needed