Normal Probabilities

Normal Probabilities

Multiple Choice

If the mean number of words typed is 40 with a standard deviation of 7, what percentage of people type more than 26 words per minute?

• 2.5%

• 13.5%

• 84%

• 95%

• 97.5%

Multiple Choice

If the mean number of words typed is 40 with a standard deviation of 7, what percentage of people type less than 47 words per minute?

• 2.5%

• 13.5%

• 84%

• 95%

• 97.5%

Multiple Choice

If the mean number of words typed is 40 with a standard deviation of 7, between what number of words type do 95% of all people type

• 19 - 61 words

• 26 - 54 words

• 33 - 47 words

• 47 - 61 words

• 19 - 54 words

Open Ended

Will Rachel's Z-score be positive, negative, or zero? Explain your answer.

Fill in the Blanks

Rachel can type 52 words per minute. If the number of typed words follows an approximately Normal distribution, with a mean of 40 and the standard deviation of 7, Rachel's Z-score will be

(Round answer to 2 decimal places)

Open Ended

Explain what Rachel's Z-score of Z = 1.71 mean in context of this scenario.

Multiple Choice

Which curve below represents the percentage of people who typed more words than Rachel in a minute?

Multiple Choice

Find the value for

P(Z > 1.78)

• 0.0376

• 0.0375

• 0.0446

• 0.2420

Multiple Choice

Find the value for 
P(Z < -0.39)

• 0.3498
• 0.3483
• 0.3501
• 0.6502

Multiple Choice

Fernando is 60 inches tall. The average height for his age and gender is 68 with a standard deviation of 10 inches. Assuming height follows a Normal distribution, what percent of his peers are shorter than him?

• 46.81%

• 8%

• 78.81%

• 21.19%