Police cars, ambulances, and other emergency vehicles are required to carry road flares. One of the most important features of flares is their burning times. To help decide which of four brands on the market to use, a police laboratory technician measured the burning time for a random sample of 10 flares of each brand. The results were recorded
to the nearest minute.
Can we conclude that differences exist between the burning times of the four brands of flares? (@25%)
Q2 (Refer to DataA2_Q2) The headrests on a car’s front seats are designed to protect the driver and front-seat passenger from whiplash when the car is hit from behind. The frame of the headrest is made from metal rods. A machine is used to bend the rod into a U-shape exactly 440 millimeters wide. The width is critical; too wide or too narrow and it won’t fit into the
holes drilled into the car seat frame. The company has experimented with several different metal alloys in the hope of finding a material that will result in more headrest frames that fit. Another possible source of variation is the machines used. To learn more about the process the operations manager conducts an experiment. Both of the machines are used to produce 10 headrests from each of the five metal alloys now being used. Each frame is measured and the data (in millimeters) are recorded using the format shown here. Analyze the data to determine whether the alloys, machines, or both are sources of variation. (@25%)
Column 1: Machine 1, rows 1 to 10 alloy A, rows
11 to 20, alloy B
Column 2: Machine 2, rows 1 to 10 alloy A, rows
11 to 20, alloy B
Q3 (Refer to DataA2_Q3) National news on television features commercials describing pharmaceutical drugs that treat ailments that plague older people. Apparently, the major networks believe that older people tend to watch national newscasts. The marketing manager of a drug company conducted a survey that took a random sample of people older than 60 years of age and recorded their age and the number of days they watched national on television
in a typical week.
a. Test to determine whether there is enough evidence to conclude that there is a linear relationship between age and number of days watching national news.(@15%)
b. Calculate the coefficient of determination and briefly describe what it tells you.(@10%)