Answer: d .we are 99% confident that the true mean age of horses with laminitis is between 6.3 and 7.4 years old.
Step-by-step explanation:
Given : Veterinary researchers at a major university veterinary hospital .
He calculated a 99% confidence interval for the average age of horses admitted for laminitis, a foot disease that leaves the horse severely lame, as 6.3 to 7.4 years.
Here , Population parameter = Mean age of horses with laminitis
Interpretation: We are 99% sure that the true mean age of horses with laminitis is between 6.3 and 7.4 years old.
Hence, the correct option is d .we are 99% confident that the true mean age of horses with laminitis is between 6.3 and 7.4 years old.