statistics

A For the following system of equations in echelon form, tell how many solutions there are in nonnegative integers. 2x +2y +2z =80 y - 2z = 10 3 A bank teller has a total of 66 bills in five-, ten-, and twenty-dollar denominations. The total value of the money is $750. (a) Find the total number of solutions. (b) Find the solution with the smallest number of five-dollar bills. (c) Find the solution with the largest number of five-dollar bills. C For the following table of data, a. Draw a scatterplot. b. Calculate the correlation coefficient. x 1 2 3 4 5 6 7 8 9 10 c. Calculate the least squares line and y 0.1 0.8 1.1 2.1 2.6 3.1 3.1 4.1 4.6 5.1 graph it on the scatterplot. d. Predict the y-value when x is 11. The table shown gives the national average pupil-teacher ratio in public schools over selected years. Year Ratio a. Find the equation for the least squares line. Let x correspond to the number of years 1991 16.4 since 1991 and let y correspond to the average number of pupils per 1 teacher. 1995 16.7 b. Use the answer from part (a) to predict the pupil-teacher ratio in 2020. Does this 1999 15.9 seem realistic? 2003 15.2 c. Calculate and interpret the correlation coefficient. 2007 13.8