Answer
P = 0.1131. Since the probability is not large, the new system is not much effective.
Work Step by Step
Here we have n = 40
$σ_{x̅} = \frac{σ}{n} = \frac{13.1 }{\sqrt 40} = 2.07$
$z = \frac{x̅ - μ_{x̅}}{σ_{x̅}} = \frac{56.8 - 59.3}{2.07} = -1.21$
$P(X \leq 56.8) = P(z < -1.21) = P(z > 1.21) = 0.1131$
