Question
A set of data items is normally distributed with a mean of 23 and a standard deviation of 5.8 . Find the data value in the distribution that corresponds to each of the following \( z \)-scores. Round your answers to the nearest tenth. (a) \( z=-1.2 \) (b) \( z=1.43 \)
Ask by Graham Carter. in the United States
Feb 04,2025
Real Tutor Solution
Tutor-Verified Answer
Answer
The data values are:
- (a) 16.0
- (b) 31.3
Solution
To find the data value \( x \) corresponding to a given \( z \)-score in a normally distributed dataset, you can use the following formula:
\[
x = \mu + z \cdot \sigma
\]
where:
- \( \mu \) is the mean of the distribution.
- \( \sigma \) is the standard deviation.
- \( z \) is the z-score.
Given:
- Mean (\( \mu \)) = 23
- Standard deviation (\( \sigma \)) = 5.8
Let's calculate the data values for each \( z \)-score.
### (a) \( z = -1.2 \)
\[
x = 23 + (-1.2) \cdot 5.8
\]
\[
x = 23 - (1.2 \times 5.8) = 23 - 6.96 = 16.04
\]
Rounded to the nearest tenth:
\[
x \approx 16.0
\]
### (b) \( z = 1.43 \)
\[
x = 23 + 1.43 \cdot 5.8
\]
\[
x = 23 + (1.43 \times 5.8) = 23 + 8.294 = 31.294
\]
Rounded to the nearest tenth:
\[
x \approx 31.3
\]
**Final Answers:**
- **(a)** The data value is **16.0**.
- **(b)** The data value is **31.3**.
Reviewed and approved by the UpStudy tutoring team
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Beyond the Answer
To find the data value that corresponds to a given \( z \)-score in a normal distribution, you can use the formula: \[ X = \mu + z \cdot \sigma \] where \( X \) is the data value, \( \mu \) is the mean, \( z \) is the \( z \)-score, and \( \sigma \) is the standard deviation. (a) For \( z = -1.2 \): \[ X = 23 + (-1.2) \cdot 5.8 = 23 - 6.96 = 16.04 \] Rounded to the nearest tenth, \( X = 16.0 \). (b) For \( z = 1.43 \): \[ X = 23 + 1.43 \cdot 5.8 = 23 + 8.294 = 31.294 \] Rounded to the nearest tenth, \( X = 31.3 \). Final answers: (a) \( 16.0 \) (b) \( 31.3 \)