ProbStat Finnias

Z-scores

100

What is the Z-Score formula?

Z= x-mean/standard deviation

200

With Z scores, what do the mean and standard deviations equal EVERY TIME?

Mean is 0, Standard Deviation is 1

300

If a data point is 2.5 standard deviations below the mean, what is its Z-score?

-2.5

400

A local bread delivers bread to cafes every morning. The delivery times are normally disturbed with a mean of 45 minutes and a standard deviation of 5 minutes. A certain delivery takes 40 minutes. What is its Z-score?

1

500

Two friends are comparing their test results. Friend 1 was at the 40th percentile and Friend 2 had a Z-score of -0.218. Which friend performed better?

Friend 2

Using the Normal Function

100

What goes in the parenthesis? normalcdf (__,__,__,__)

lower, upper, mean, standard deviation

200

What does cdf mean in normalcdf?

Cumulative Distribution Function

300

The distribution of wait times at a doctor is normally distributed with a mean of 30 minutes and a standard deviation of 4.3 minutes. What percent of the wait times is less than 25 minutes?

12.2%

400

The distribution of speed is normally distributed with a mean of 80 mph and a standard deviation of 7.7 mph. What percent of attempts will have a speed greater than 85 mph?

25.8%

500

After accelerating for 20 seconds from a stop, a DeLorean sports car has a wide range of speeds that it can achieve, depending on traction. For many attempts, the distribution of speed follows an approximately normal distribution with a mean of 80 mph and a standard deviation of 7.7 mph. What percent of the attempts will give the DeLorean a speed less than 68.45 mph? 9.25% is an ESTIMATE, get the EXACT answer

6.68%

Using the Inverse Normal Function

100

What goes in the parenthesis? InvNorm (___,___,___)

area, mean, standard deviation

200

You already have the area, so what are you using InvNorm to find?

the boundary

300

The distribution of wingspans for a certain hawk species is normally distributed with a mean of 49 inches and a standard deviation of 3.5 inches. If a wingspan is at the 97th percentile, what is the hawk's wingspan, in inches?

55.58 inches

400

The diameters of grapefruits grown in a Florida orchard are approximately normally distributed with a mean of 4.5 inches and a standard deviation of 0.4 inches. The middle 50% of grapefruits at this orchard fall between which two diameter lenghts?

4.23 inches, 4.77 inches

500

The distribution of distances traveled by paddle boarders is normally distributed with a mean of 2.8 and a standard deviation of 0.5. Find the distances at the 20th and 80th percentiles.

2.38 inches, 3.22 inches