At One School, the Mean Amount of Time That Tenth-Graders $\mathrm { H } _ { 0 } : \mu = 18.4$

At one school, the mean amount of time that tenth-graders spend watching television each week is 18.4 hours. The principal introduces a campaign to encourage the students to watch less television.
One year later, the principal wants to perform a hypothesis test to determine whether the average amount of time spent watching television per week has decreased. Formulate the null and alternative hypotheses for the study described.

A) $\mathrm { H } _ { 0 } : \mu = 18.4$ hours
$\mathrm { H } _ { \alpha } : \mu \neq 18.4$ hours

B) $H _ { 0 } : \mu = 18.4$ hours
$\mathrm { H } _ { \alpha } : \mu < 18.4$ hours

C) $\mathrm { H } _ { 0 } : \mu \geq 18.4$ hours
$\mathrm { H } _ { \alpha } : \mu < 18.4$ hours

D) $\mathrm { H } _ { 0 } : \mu = 18.4$ hours
$\mathrm { H } _ { \alpha } : \mu > 18.4$ hours