Statistics and Probability Practice Quiz No. 4

In a normal distribution, how many modes are there?

• 3

• 2

• 1

• 0

Answer explanation

A normal distribution is unimodal.

What is the sum of the area under the normal curve?

• 0

• 1

• 10

• 100

Answer explanation

The area under the normal curve is also a probability.

Which value of the standard deviation with equal means will make the normal curve the most elevated?

• 0.25

• 0.28

• 0.31

• 0.34

Answer explanation

The lower the standard deviation in a normal distribution, the more elevated the normal curve.

• 0.2389

• 0.2358

• 0.7642

• 0.7611

Answer explanation

• 0.9300

• 0.0930

• 0.0564

• 0.1248

Answer explanation

What is the unit of measurement for z-scores?

• standard deviation
• variance

• percentage

• proportion

Answer explanation

The z-scores found in the x-axis are one standard deviation away from each other.

• 65.8

• 73.3

• 78.3

• 85.8

Answer explanation

Determine the equivalent z-score of 105 in normal distribution with mean of 100 and standard deviation of 12.

• 0.41

• 1.25
• 0.85
• 2.17

Answer explanation

In a numeracy test, the average score is 88.5 with a standard deviation of 12.5. What is the probability that the score will be less than 97?

• 0.6745
• 0.8413

• 0.7517

• 0.9772

Answer explanation

The mean time of a certain brand of android phone to be fully charged is 1.5 hours with a standard deviation of 0.4 hours. Determine the probability that the time of the android phone to be fully charged is greater than 1 hour.

• 0.8944

• 0.1056

• 0.1075

• 0.8925

Answer explanation