Elementary Statistics (12th Edition)

a) By using the table, the z-score corresponding to 0.95: z=0.52 and z= 1.645. Hence the corresponding values:$mean+z⋅standard \ deviation=1511+1.645⋅312=2024.24.$ $mean+z⋅standard \ deviation=21.1+1.645⋅5.1=29.49.$ b)$z=\frac{value-mean}{standard \ deviation}=\frac{2100-1511}{312}=1.89.$ Hence the corresponding value:$mean+z⋅standard \ deviation=21.1+1.89⋅5.1=30.74.$