QUIZ - 5.1- 5.3 Normal Distribution

In a STANDARD NORMAL distribution, the mean and standard deviation are:

• I hope you have a great Christmas break. :)

Which of these is the formula for finding a z-score?

• Happy New Year...Soon!

Which of these is the formula for finding a value if you are given the z-score?

• Happy New Year...Soon!

Determine whether the following graph can represent a variable with a normal distribution. Explain your reasoning. If the graph appears to represent a normal​ distribution, estimate the mean and standard deviation.

• No, because the graph is skewed right.

• ​No, because the graph is skewed left.

• ​Yes, the graph fulfills the properties of the normal distribution. The mean is approximately 30

  and the standard deviation is about

  5

• Yes, the graph fulfills the properties of the normal distribution. The mean is approximately 18

  and the standard deviation is about

  4

Find the area of the indicated region under the standard normal curve.

• 0.8080

• 0.8181

• 0.7272

• 0.7224

A standardized​ exam's scores are normally distributed. In a recent​ year, the mean test score was

1489 and the standard deviation was 312.

The test score of a student selected at random is 2160​,

Find the​ z-score that correspond to the value and determine whether the value is unusual.

• z = 2.15 and is unusual

• z = 2.15 and is NOT unusual

• z = 0.15 and is unusual

• z = 0.15 and is NOT unusual

Find P(z > -0.41)

• 0.5440

• 0.3409

• 0.6591

• 0.1590

Assume the random variable x is normally distributed with mean μ=80

and standard deviation σ=5.

Find the indicated probability. Find P(67 < x < 72)

• 0.0501

• 0.0269

• 1

• 0.1051

The monthly utility bills in a city are normally​ distributed, with a mean of ​$100

and a standard deviation of ​$16.

Find the probability that a randomly selected utility bill is​ more than ​$130.

• 0.0144

• 0.3825

• 0.0304

• -0.3825

According to the normal distribution graphed, out of 1500 randomly selected​ scores, about how many would be expected to be greater than​ 21?

• 41.93

• 651

• 419.3

• 649