Recall from Chapter 2, we had two main calculator functions that were used:

• normalcdf(lower bound, upper bound, mean, st dev): used to find the area under the Normal distribution between two bounds
  • Example: IQ scores are normally distributed with mean 100 and a standard deviation of 15. Calculate the proportion of individuals that have IQ scores above 135.
  • Solution: normalcdf(135, ∞, 100, 15) ≈ 0.0098 --> approx 1%
• invNorm(area under the Normal distribution to the LEFT of a z-score ("percentile"), mean, st dev): used to find the z-score or observation in a Normal distribution that is located at the nth percentile. 
  • Example: IQ scores are normally distributed with mean 100 and a standard deviation of 15. Mr Mills claims he scored in the 98th percentile on an IQ test. What is his IQ score?
  • Solution: invNorm(0.98, 100, 15) ≈ 130.81

Answer the following questions below using your knowledge from Chapter 2