Recognizing Normal Distributions

The weights of adult male beagles are normally distributed, with a mean of 25 pounds and a standard deviation of 3 pounds. A beagle is randomly selected. Find the probability that the beagle’s weight is between 23 and 26 pounds.

• 0.3694
• 0.3781
• 0.0912

The weights of adult male beagles are normally distributed, with a mean of 25 pounds and a standard deviation of 3 pounds. A beagle is randomly selected. Find the probability that the beagle’s weight is more than 29 pounds.

• 0.3694
• 0.3781
• 0.0912

A z-score tells you...

• the standard deviation of a sampling distribution.
• the original raw score on which it is based.
• if the distribution it comes from is normal.
• how many standard deviations away from the mean a score lies.

Which is NOT true about the standard normal distribution?

• It is bell-shaped.
• It is unimodal.
• The mean is 0 and the standard deviation is 1.
• It is asymmetrical.

Find the area under the standard normal curve between z = -2.55 and z = 1.08. 

• 0.8545
• 0.7560
• 0.3110
• 0.2140

Find the area under the standard normal curve to the right of z = -2.67.

• 0.0869
• 0.9962
• 0.0008
• 0.1234

The test scores for the exam in statistics class have a mean of 78 points and standard deviation of 9 points. A student is randomly selected. Assuming the scores are normally distributed find the probability that the score is between 80 and 90.

• 0.0295
• 0.00000005
• 0.3209
• 4.32

The mean temperature in Glens Falls for the month of February is 23 degrees with a standard deviation of 4.2 degrees. What is the z-score for a temperature of 17 degrees?

• 1

• 1.43

• -1.43

• 11.5

Calculate the z score of your value if the mean is 75, your score is 90 and the standard deviation is 4.5

• -3.33
• 3.33

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.