Statistics Quiz Unit 5 Day 1-Day 2 ZScores Assignment #3

The mean life of a tire is 30,000 km. The standard deviation is 2000 km.

Then, 68% of all tires will have a life between ___________ km and __________ km.

•  28,000 km and 32,000 km.
• 24,000 km and 34,000 km.
• 26,000 km and 34,000 km.
• 27,000 km and 31,000 km.

Tags

CCSS.HSS.ID.A.4

The average waist size for teenage males is 29 inches with a standard deviation of 2 inches. 
If waist sizes are normally distributed, determine the z-score of a teenage male with a 33 inch waist.  

• 2
• 1
• -2
• -1

Tags

CCSS.HSS.ID.A.4

The shelf life of a particular dairy product is normally distributed with a mean of 12 days and a standard deviation of 3 days.

About what percent of the products last between 12 and 15 days?

• 68%
• 34%
• 16%
• 2.5%

Tags

CCSS.HSF-LE.A.1B

By the way, what is standard deviation?

• good question

• how standardly something deviates

• average distance that data points are from the average

• Idk but I should probably find out pretty soon

Tags

CCSS.HSS.ID.A.4

CCSS.HSS.ID.A.2

CCSS.HSS.ID.A.3

Brian scored an 80% on a Chemistry Exam. The average on the exam was a 68%, with a standard deviation of 5%. What is Brian's z-score?

• 2.4

• -2.4

• 1.1

• -1.1

Tags

CCSS.HSS.ID.A.4

Scores on the ACT form a normal distribution with a mean of 21 and a standard deviation of 5.2. What is the minimum score necessary to be in the top 12% of the ACT distribution?

• 24

• 14.9

• 27.1

• 29.2

What is the percentile rank(percent of individuals) that has a z-score below -1.27

• 0.898 or 89.8%

• 0.102 or 10.2%

• 0.500 or 50%

• 0.333 or 33.3%

Scores on the ACT form a normal distribution with a mean of 21 and a standard deviation of 5.2. What is the score of someone that is in the upper 5% of the distribution.

• 12.4

• 21

• 27.1

• 29.6

The shelf life of a particular dairy product is normally distributed with a mean of 14 days and a standard deviation of 4 days. About what percent of the dairy products last between 10 and 18 days? Give your answer in the nearest percent, i.e. 25%

(a)  

The mean battery life of a battery is 45 hours with a standard deviation of 4.3 hours. The manufacturer advertises that they will replace all batteries that last less than 38 hours for free. If you bought 500 batteries, how many would you expect to be replaced for free?

• between 5 and 6 batteries

• between 15 and 16 batteries

• between 25 and 26 batteries

• between 474 and 475 batteries