QUIZ 2
Name
Prob. 1 The accompanying figures were compiled by Clarke, Kingsley, and Company, a consulting firm that specializes in auto operating costs, relating the annual mileage (in thousands of miles) that an average new compact car is driven to the cost per mile (in cents) of operating the car.
a. Determine an equation of the least-squares line for these data.
Using the calculator we get the linear regression line
b. Use the result obtained in (a) to estimate the cost per mile of operating a new company car if it is driven 8000 miles during the first year of ownership.
Note that the mileage in the table is given in thousands. Thus, 8000 should be entered as 8. We get that the cost per mile is
or $40.87
Prob. 2 The annual interest on Mr. Carrington's three investments amounted to $21,600: 6% on a savings account, 8% on mutual finds, and 12% on money-market certificates. If the amount of Carrington's investment is money-market certificates was twice the amount of his investment in the savings account, and the interest earned from his investment in money-market certificates was equal to the dividends he received from his investment in mutual funds, find how much money he place in each type of investment. (Set up, but do not solve the system of equations needed to solve this problem.)
We let
x = amount in savings account;
y= amount in mutual funds;
z= amount in money market certificates.
Thus, the total amount earned is
We have the statement that the amount of money-market certificates was twice the amount of his investment in the savings account which gives the following equation:
Finally, we know that interest earned from his investment in money-market certificates was equal to the dividends he received from his investment in mutual funds so,
We have the following system.
