Answer:
Step-by-step explanation:
Hello!
The researchers want to compare the weight of the basset hounds in 1915 with the weight of the basset hound in 2015.
Using a sample of 36 male basset hounds taken in 1915 and a sample of 36 male basset hounds taken in 2015 a 90% CI for the difference of mean weights of the basset hounds (2015-1915) was constructed:
Group 1
X₁: Weight of a basset hound measured in 1915
n₁= 36
Group 2
X₂: Weight of a basset hound measured in 2015
n₂= 36
Difference X₂ - X₁
X[bar]₂ - X[bar]₁= -2.8cm
margin of error d= 1.3cm
90% CI: [-1.4; -1.5]cm
The calculated CI is two-tailed, you can use it to decide over a two-tailed hypothesis test for the same parameter of interest over the same level. If the hypothesis is:
H₀: μ₂ - μ₁=0
H₁: μ₂ - μ₁≠0
α: 0.10
The CI doesn't contain the zero, so you could reject the null hypothesis. With this, you can conclude that the difference between the average weight of the basset hounds in 2015 and the average weight of the basset hounds in 1915.
Judging by the fact that both limits of the confidence interval are negative, as well as the difference between point estimators, it seems that the weight of the basset hounds in 2015 is less than their weight in 1915. Of course, you are not valid to make that kind of conclusion without a proper hypothesis test.
