Global use of cell phones grew rapidly between 1989 and 2000. below is a scatterplot of the percentage of people in the world who are cell phone subscribers versus year for this time interval, along with the residual plot from a linear regression analysis. (a) is a linear model appropriate for these data? justify your answer. (b) below is a scatterplot of the natural logarithm of cell phone subscribers vs. year. this relationship is clearly more linear that the one above. does this suggest that the relationship between cell phone subscribers and year can be modeled by an exponential function or by a power function? explain. (c) computer output from the regression of ln (cell phone subscribers) vs. year is given below. use it to predict the percentage of people in the world who were cell phone subscribers in 2005. (d) comment on the reliability of this prediction.

Companies in the u.s. car rental market vary greatly in terms of the size of the fleet, the number of locations, and annual revenue. in 2011 hertz had 320,000 cars in service and annual revenue of approximately $4.2 billion. the following data show the number of cars in service (1000s) and the annual revenue ($ millions) for six smaller car rental companies (auto rental news website, august 7, 2012). excel file: data14-09.xls if required, enter negative values as negative numbers. a. select a scatter diagram with the number of cars in service as the independent variable. b. what does the scatter diagram developed in part (a) indicate about the relationship between the two variables? c. use the least squares method to develop the estimated regression equation (to 3 decimals). ŷ = + x d. for every additional car placed in service, estimate how much annual revenue will change. by $ e. fox rent a car has 11,000 cars in service. use the estimated regression equation developed in part (c) to predict annual revenue for fox rent a car. round your answer to nearest whole value. $ million hide feedback partially correct

Turrubiates corporation makes a product that uses a material with the following standards standard quantity 8.0 liters per unit standard price $2.50 per liter standard cost $20.00 per unit the company budgeted for production of 3,800 units in april, but actual production was 3,900 units. the company used 32,000 liters of direct material to produce this output. the company purchased 20,100 liters of the direct material at $2.6 per liter. the direct materials purchases variance is computed when the materials are purchased. the materials quantity variance for april is:

In 1975, mcdonald’s introduced its egg mcmuffin breakfast sandwich, which remains popular and profitable today. this longevity illustrates the idea of: