Answer:
z(s) = - 0.7740
Step-by-step explanation:
Normal Distribution
sample size n = 140
sample mean 68.3
A ne tailed-test to the left from problem statement
1.-Test hypothesis
H₀ null hypothesis μ₀ = 69
Hₐ alternative hypothesis μ₀ < 69
2.- To find a value of test statistics z(s)
z(s) = [ ( μ - μ₀ ) /( σ /√n )
z(s) = ( 68.3 - 69 ) / (10.7/√140) ⇒ z(s) = - 0.7*11.83 /10.7
z(s) = - 0.7740