This lab can be completed by calculating standard scores using the formula

and using Table B on p. 668 of the text.

As an alternative, this lab can be completed using the graphing calculator by accessing the Distribution Menu (2^nd key, then VARS) and using the following functions:

1. To find a percentile given an observation, use normalcdf(Lower Bound, Upper Bound, Mean, Standard Deviation).

For left-tailed areas use - 99999 as the lower bound. For right-tailed areas use 99999 as the upper bound.

1. To find an observation given a percentile, use invNorm(Percentile, Mean, Standard Deviation).
   1. 68% of the actors received Oscars between the ages of ________ and ________.

Remember, the percentile is the left tail area for the value that you want. So invNorm always requires left tail area.

In the last lab, we discovered that the ages of Oscar winning actors for the last 23 yearsis roughly symmetric and mound shaped. The distribution of ages for all Oscar winning actors at the time they receive the award is approximately normal with a mean of 44 years and standard deviation of 9 years.

The 68-95-99.7 Rule

1. 95% of the actors received Oscars between the ages of _________ and ________.

1. 99.7% of the actors received Oscars between the ages of ________ and ________.

Finding Percentiles

1. The oldest actor to win the Oscar was Henry Fonda at age 76 for his performance in 'On Golden Pond'. What percent of actors received the Oscar after the age of 70?How does this percentage compare to the probability of an actor receiving the Oscar after the age of 70 if there is only one actor older than 70 who won the Oscar in the 85 years that the Oscar has been awarded? (HINT:draw the picture of the area that represents this probability. You will notice that it is a right-tailed area.)

1. Actors who receive the Oscar before their 25^th birthday are considered exceptional. What percent of actors received the Oscar before age 25? (HINT: draw the picture of the area that represents this probability. You will notice that it is a left-tailed area.)

1. What percent of actors received the Oscar between the ages of 55 and 70?

Finding Observations Given a Percentile

1. The top 10% of actors received the Oscar after the age of _______.

1. The bottom 20% of actors received the Oscar before the age of _________.