Math Problem Statement
5. A measurement x in a sample with mean 2.3 and standard deviation 1.3 has a z-score equal to -2.
What is x?
[A] -0.3 [B] 4.6 [C] 4.9 [D] -2.6
Solution
To solve for the value of x given that the z-score is -2, the mean is 2.3, and the standard deviation is 1.3, we can use the formula for the z-score:
Where:
- is the z-score,
- is the mean,
- is the standard deviation, and
- is the value we're solving for.
Plugging in the known values:
Now, solve for :
-
Multiply both sides by 1.3:
-
Add 2.3 to both sides:
Thus, the value of x is , which corresponds to option [A] -0.3.
Would you like more details on z-scores or any further explanations?
Here are 5 related questions to explore this topic further:
- How would the z-score change if x was greater than the mean?
- What does a z-score of 0 represent in a dataset?
- How do you interpret positive and negative z-scores in terms of standard deviations?
- How can z-scores be used to compare measurements from different datasets?
- What is the relationship between the standard deviation and the spread of data?
Tip: A z-score represents how many standard deviations a data point is from the mean. A negative z-score indicates the point is below the mean.
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Math Problem Analysis
Mathematical Concepts
Statistics
Z-score
Standard Deviation
Mean
Formulas
z = (x - μ) / σ
Theorems
-
Suitable Grade Level
Grades 9-12
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