Percentile Rank Computation

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. What weight falls at the 50th percentile?

• 1106 pounds

• 1150 pounds

• 1128 pounds

• 1172 pounds

Answer explanation

1150

Scores on a certain standardized test have a mean of 500, and a standard deviation of 100. What score would you need to fall at the 84th percentile?

• 84

• 400

• 500

• 600

 

At a local high school, GPAs are normally distributed with a mean of 2.9 and a standard deviation of 0.6. If you have a GPA of 4.1, what is your percentile?

• 50th

• 98th

• 84

• 2.5

The mean life of a tire is 30,000 km. The standard deviation is 2000 km. What is the z-score of a tire that lasts 27, 500 miles. What percentile is this?

• z=-1.25, 9th percentile

• z=-1.25, 11th percentile

• z=-2.25, 11th percentile

• z=-1.25, 8th percentile

At a high school, GPAs are normally distributed with a mean of 2.9 and a standard deviation of 0.6. Find the z-score of a GPA of 3.2? What percentile is this?

• z=0.5, 65th percentile

• z=0.5, 69th percentile

• z=0.5, 67th percentile

• z=1.5, 69th percentile