Warm-up 2.5 Day 2

1)An incoming freshman took her college’s placement examsin French and mathematics. In French, she scored 82 and inmath, 86. The overall results on the French exam had amean of 72 and a standard deviation of 8, while the meanmath score was 68 with a standard deviation of 12. Onwhich exam did she do better compared with the otherfreshmen?

Warm-up Day 22) Two companies market new batteries targeted at owners of personal music players. DuraTunes claims a mean battery life of 11 hours, while RockReady advertises 12 hours. a) Explain why you would also like to know the standard deviations of the battery lifespans before deciding which brand tobuy.b) Suppose those standard deviations are 2 hours for DuraTunes and 1.5 hours for RockReady. You are headed for 8 hours at thebeach. Which battery is most likely to last all day? Explain.c) If your beach trip is all weekend, and you probably will havethemusic on for 16 hours, which battery is most likely to last? Explain.

Mooseburger vs.McTofu

3)M-burgers’s weekly payroll number are mostly higherthan McTofu. McTofu has an outlier that is out of place.

McTofu vs. Mooseburger4) On average Mooseburger pays the highersalaries.

5) The mean salary is misleading for McTofubecause it has an outlier which will make the meanpayroll considerably higher.

6) Mooseburger has consistently higher payrolls,McTofu has one high payroll number which may bea manager. This McTofu’s numbers misleading.

Student of the Day!Block 4

Student of the Day!Block 5

Student of the Day!Block 6

Z-scoreZ-scores (for normal distribution) describe how manystandard deviations (σ) a piece of data is from themean(μ).

The z-score can also be used to find the proportion ofvalues above or below the z-score using normalcdf (z-score, upper or lower bound)

invNorm is for finding the z-score when the percentile, mean and standard deviation is given.

invNorm(percentile,mean, standard deviation)

x

z

Practice with z-scores and finding proportions.1) A distribution of quiz scores has a mean of 35 andan standard deviations of of 4. Sara received a 40. a) What is her z-score?b) What is her percentile rank compared to the restof the class?

2) In a normal distribution with mean 25 and standarddeviation 7, what proportion of the data are less than 20?

Multiple Choice Practice • Answer 1 – 10 by yourself.• Once everyone at your table is done, discuss youranswers.• Submit your group answers on a separate piece ofpaper to be graded for accuracy.

H.W.

E #63- 65. Draw the bell curve and label standard deviations for each of the problems.