Question

matteo wants to determine the z - score for his monday expenses to see if it is greater than or less than the average. the mean for his weekly expenses is $15 and the standard deviation is $3.16. recall that the formula for a z - score is $z=\frac{x - mu}{sigma}$. if he spent $11 on monday, what is the z - score? his monday expenses are <the mean of his weekly expenses.

Explanation:

Step1: Identify values

Let $x = 11$ (Monday - expense), $\mu=15$ (mean), $\sigma = 3.16$ (standard - deviation).

Step2: Apply z - score formula

The z - score formula is $z=\frac{x - \mu}{\sigma}$. Substitute the values: $z=\frac{11 - 15}{3.16}$.

Step3: Calculate the numerator

$11−15=-4$.

Step4: Calculate the z - score

$z=\frac{-4}{3.16}\approx - 1.27$.

Answer:

$-1.27$