A vet was interested in seeing if there was a difference in the number of pets that someone owned based on if they spayed or neutered their pets. Group 1 did not spay/neuter their pets and Group 2 did spay/neuter their pets. The 95% confidence interval was (-2.77, -0.42). Finish the following sentence "We are 95% confident that . . .

a. the population mean number of pets owned by people that did not spayed/neutered their pet was between 0.4 to 2.77 pets less than those who did spay or neuter their pet.
b. the population mean number of pets owned by people that did not spayed/neutered their pet was between 0.4 to 2.77 pets more than those who spay or neuter their pet.
c. the population mean number of pets owned by people that did not spayed/neutered their pet was between 0.4 less pets to 2.77 pets more than those who spay or neuter their pet.

Interpreting the 95% confidence interval, it is found that the correct option is

a. the population mean number of pets owned by people that did not spayed/neutered their pet was between 0.4 to 2.77 pets less than those who did spay or neuter their pet.

The interval for Group 1 - Group 2 is (-2.77, -0.42), that is, the mean number for those who did not spray/neuter the pet is less than those who did, hence, option a is correct.

A similar problem is given at link

The correct option is (a).

Step-by-step explanation:

The (1 - α)% confidence interval for population parameter implies that there is a (1 - α) probability that the true value of the parameter is included in the interval.

Or, the (1 - α)% confidence interval for the parameter implies that there is (1 - α)% confidence or certainty that the true parameter value is contained in the interval.

The 95% confidence interval for the difference between the mean number of pets who were not spayed/neutered from that of those who were spayed/neutered is,

CI = (-2.77, -0.42).

The number of pets who were not spayed/neutered is labelled as Group 1.

The number of pets who were spayed/neutered is labelled as Group 2.

The parameter under study is:

μ₁ - μ₂

The 95% confidence interval for the difference of means implies that there is a 95% confidence that the population mean number of pets owned by people that did not spayed/neutered their pet was between 0.42 to 2.77 pets less than those who did spay or neuter their pet.

Thus, the correct option is (a).