Answer: t-statistic > t-critical, we reject the null hypothesis.
Therefore, we conclude that kaiser claim is valid.
Step-by-step explanation:
In this question,
Null hypothesis,
: Actual cost of rehabilitation is greater than $28,500
Alternative Hypothesis,
: Actual cost of rehabilitation at most $28,500
the medical billing records of 45 football players, n = 45
\bar{X} ⇒ average cost for rehabilitation = $30,885
: u > 28500 ⇒ Kaiser claims is not valid
: u ≤ 28500 ⇒ Kaiser claims is valid
t - statistic =

=

= 14.25
From the t- distribution, with degree of freedom = n-1 ⇒ 45-1 = 44 and level of significance 0.05
t-critical value = 1.6802
So,
t-statistic > t-critical, we reject the null hypothesis.
Therefore, we conclude that kaiser claim is valid.