An advertising company is curious about the impact the lengths of their television advertisements have on viewers' feelings about a product. They showed advertisements of different lengths to a group of volunteers and
asked the volunteers to rate how positive they felt about the product on a scale of 1 to 10. Their data is shown
in the table below.
Avg. product rating
6.0
7.0
5.0
3.0
2.5
Ad length (seconds)
30
45
60
75
90
All of the scatter plots below display the data correctly, but which one of them displays the data best?
By convention, a good scatter plot uses a reasonable scale on both axes and puts the explanatory variable on the c-
axis.

Amachine that produces a special type of transistor (a component of computers) has a 2% defective rate. the production is considered a random process where each transistor is independent of the others. (a) what is the probability that the 10th transistor produced is the first with a defect? (b) what is the probability that the machine produces no defective transistors in a batch of 100? (c) on average, how many transistors would you expect to be produced before the first with a defect? what is the standard deviation? (d) another machine that also produces transistors has a 5% defective rate where each transistor is produced independent of the others. on average how many transistors would you expect to be produced with this machine before the first with a defect? what is the standard deviation? (e) based on your answers to parts (c) and (d), how does increasing the probability of an event a↵ect the mean and standard deviation of the wait time until success?