Chapter 5 - Normal Probability Distributions - Section 5.4 Sampling Distributions and the Central Limit Theorem - Exercises - Page 271: 28

Hence 13.57% of flight attendants will have mean salary less than $63,400

To calculate P(x̄ < 63400), we need to find the z-score: $z = \frac{x̄ - μ_{x̄}}{σ/\sqrt n}$ $= \frac{63400 - 65700}{14500/\sqrt 48}$ = -1.10 P(z < -1.10) = 0.1357, hence: P(x̄ < 60000) = 0.1357