Answer:
Point Estimate for different between population means = - 0.99
Step-by-step explanation:
We are given data of two samples and we have to find the best point estimate of the true difference between two population means. Remember that in absence of data about population the best estimator is the sample data. So, we will find the means of both sample data and find the difference of that means. This difference between the means of sample data will be the best point estimate for the true difference between the population means.
Formula to calculate the mean is:

Mean of Sample 1:

Mean of Sample 2:

Therefore the best point estimate for difference between two population means would be = Mean of Sample 1 - Mean of Sample 2
= 128.55 - 129.54
= - 0.99
84 in I believe? (Im sorry im not much help)
B=t-am is the correct answer:)
Use Pythagorean theorem:
9i-j = sqrt (9^2 - 1^2) = sqrt(81-1) = sqrt80
now divide both terms in V by that:
u = 9/sqrt(80)i - 1/sqrt(80)j
see attached picture:
I am not really sure but I think the answer is B