Var(uᵢ | X₁ᵢ, X₂ᵢ) = 6 and var(X₁ᵢ) = 2.
A random sample of size n = 300 is drawn from the population. Assume that X₁ᵢ and X₂ᵢ are uncorrelated.
(a) Compute the variance of ^β₁.
(b) Assume that Corr(X₁ᵢ, X₂ᵢ) = 0.9. Compute the variance of ^β₁.
(c) Comment on the following statement:
"When X₁ᵢ and X₂ᵢ are correlated, the variance of ^β₁ is larger than it would be if X₁ᵢ and X₂ᵢ were uncorrelated. Thus, if you are interested in β₁, it is best to leave X₂ out of the regression if it is correlated with X₁."

Ahome improvement store rents it’s delivery truck for $19 for the first 75 minutes and $4.75 for each additional 1/4 hour. if a customer rented the truck at 11: 10 am and returned the truck at 1: 40 pm the same day, what would his rental cost be?

The function a represents the cost of manufacturing product a, in hundreds of dollars, and the function b represents the cost of manufacturing product b, in hundreds of dollars. a(t) = 5t + 2 b(t) = 7t - 2t +4 find the expression that describes the total cost of manufacturing both products, a(t) + b(t). a. 7t^2 - 7t + 2 b. 7t^2 + 3 +6 c. 7t^2 + 7t - 6 d. 7t^2 - 3t + 6

Quick! a survey of 57 customers was taken at a bookstore regarding the types of books purchased. the survey found that 33 customers purchased mysteries, 25 purchased science fiction, 18 purchased romance novels, 12 purchased mysteries and science fiction, 9 purchased mysteries and romance novels, 6 purchased science fiction and romance novels, and 2 purchased all three types of books. a) how many of the customers surveyed purchased only mysteries? b) how many purchased mysteries and science fiction, but not romance novels? c) how many purchased mysteries or science fiction? d) how many purchased mysteries or science fiction, but not romance novels? e) how many purchased exactly two types of books?