Answer:
Step-by-step explanation:
Given that,
Sample size n= 26
Sample mean = 144.4mg
Population standard deviation = 2.9mg
a) Null and alternative hypothesis are
H₀ : μ = 145mg vs H₁ : μ ≠ 145mg
b) Test statistic is

c) the critical values at
are 
Since it is two-tailed test
Decision rule: reject H₀
If Z > +1.645 or if Z < -1.645
Here Z = - 1.05 > - 1.645
⇒ we fail to reject H₀
⇒ the sample does not contradict the manufacturers claim
d) P-value = 2* P( Z < -1.05)
= 2 * 0.1469
= 0.2938
⇒ P-value = 0.2938