AnswersConcepts in Probability and Statistics - MA3120 B-CRApplications with Standard Normal Distribution — Cumulative examQuestion 49
49
QuizMultiple Choice
Applications with Standard Normal Distribution — Cumulative exam
Question 49 • Concepts in Probability and Statistics - MA3120 B-CR
A worker at the local Department of Motor Vehicles (DMV) claims that 60% of teenagers smile in their driver’s license photo. In a random sample of 10 teenagers from last month’s new driver’s licenses, only 4 of them were smiling in their photos. To see how unusual this sample is, 100 simulated trials were conducted under the assumption that 60% of teenagers smile for their driver’s license photo.
Answer
A
The actual proportion of teenagers who do not smile is only 8%.B
It is clear that exactly 6 out of 10 teenagers will smile in their driver’s license photo.C
If we continued to take more samples of 10 teenagers, the center of the distribution would shift to 6.D
There is about an 8% chance that 4 or fewer teenagers smiled for their photo. This is not unusual and is not convincing evidence that the true probability is less than 60%.