On a entrance exam, the mean was 50 and standard deviation was 5. If Ricky's z-score was -1.5, what was his exam score?
I don't have a clue how to start to answer this question...
Would I set it up like this?
-1.5 = x-50/5???
http://davidmlane.com/hyperstat/z_table.html
To find Ricky's exam score, we can use the formula for calculating z-scores. The formula is:
z = (x - μ) / σ
Where:
- z is the z-score
- x is the value we want to find (in this case, Ricky's exam score)
- μ is the mean
- σ is the standard deviation
Given that Ricky's z-score is -1.5, the mean μ is 50, and the standard deviation σ is 5, we can substitute these values into the formula and solve for x:
-1.5 = (x - 50) / 5
To solve for x, we can multiply both sides of the equation by 5:
-1.5 * 5 = x - 50
-7.5 = x - 50
To isolate x, we can add 50 to both sides of the equation:
-7.5 + 50 = x
42.5 = x
Therefore, Ricky's exam score was 42.5.
To answer this question, you can use the formula for z-score:
z = (x - μ) / σ
Where:
z = z-score
x = individual value
μ = mean
σ = standard deviation
In this case, you know the z-score, the mean, and the standard deviation. You need to find the individual value (Ricky's exam score). Rearranging the formula, you get:
x = z * σ + μ
Now you can substitute the given values into the formula:
x = (-1.5) * 5 + 50
x = -7.5 + 50
x = 42.5
Therefore, Ricky's exam score was 42.5.