It has long been stated that the mean temperature of humans is ${98.6}^{\circ }\mathrm{F}$. However, two researchers currently involved in the subject thought that the mean temperature of humans is less than ${98.6}^{\circ }\mathrm{F}$. They measured the temperatures of 61 healthy adults 1 to 4 times dally for 3 days, obtaining 275 measurements. The samplo data resulted in a sample mean of ${98.4}^{\circ }\mathrm{F}$ and a sample standard deviation of $1^{\circ }\mathrm{F}$. Use the P-value approach to conduct a hypothesis test to judge whether the mean temperature of humans is less than ${98.6}^{\circ }\mathrm{F}$ at the $\alpha =0.01$ level of significance.

State the hypotheses.
$$\begin{array}{l}{H}_0:H_{\mu }={98.6}^{\circ }\mathrm{F}\\ H_1:\mu <{98.6}^{\circ }\mathrm{F}\end{array}$$

Find the test statistic.
$$t_0=◻$$
(Round to two decimal places as needed.)