Z Score word problems

What is the purpose of z-scores?

• to describe the exact location of a score within a distribution

• to find the mean of the distribution

• to describe the shape of the distribution

• to find the standard deviation of the distribution

Tags

CCSS.HSS.ID.A.4

What is the formula to find the z-score for population?

• z=X-M

• z=σ-M/μ

• ^z/M=μ

• z=X-μ/σ

Tags

CCSS.HSS.ID.A.4

If heights of 3rd graders follow a normal distribution with a mean of 52 inches and a standard deviation of 2.5 inches, what is the z score of a 3rd grader who is 47 inches tall? 

• -5
• -2
• 2
• 5

Tags

CCSS.HSS.ID.A.4

In a factory, the weight of the concrete poured into a mold by a machine follows a normal distribution with a mean of 1150 pounds and a standard deviation of 22 pounds. Approximately 95% of molds filled by this machine will hold weights in what interval? 

• 1084 to 1216 pounds 
• 1106 to 1150 pounds 
• 1106 to 1194 pounds 
• 1128 to 1172 pounds

Tags

CCSS.HSS.ID.A.4

A national achievement test is administered annually to 3rd graders. The test has a mean score of 100 and a standard deviation of 15. If Jane's z-score is 1.20, what was her score on the test?

• 82
• 88
• 100
• 118

Tags

CCSS.HSA.REI.B.3

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.HSS.ID.A.4

The Floppy Disk Company makes 3.5 inch floppy disks for disk drives that are 3.7 inches wide. The size of a manufactures disk is normally distributed with a standard deviation of 0.1 inches. The company manufactures 1000 disks every hour.

In one hour, how many disks would you expect to be between 3.4 inches and 3.7 inches?

• 819 disks
• 23 disks
• 500 disks
• 0 disks

Tags

CCSS.HSS.ID.A.4

CCSS.HSS.MD.A.2

CCSS.HSS.MD.A.3

CCSS.HSS.MD.B.5

Women’s heights have a mean of 63.6 in. and a standard deviation of 2.5 inches.  The z score corresponding to a woman with a height is 2.56. How tall is the woman?

• 24.42 in
• 70 in
• 28in
• 68.6in

Tags

CCSS.HSS.ID.A.4

Standard deviation tells us how spread out a symmetric distribution is. 
Since a Z-score tells us how many standard deviations away from average something is, what does a high Z-score mean?

• It's way higher than average
• tl:dr
• you're in trouble?
• you need a doctor