Question

About % of the area under the curve of the standard normal distribution is outside the interval z = [ −3, 3] (or beyond 0.12 standard deviations of the mean).

Answer 1

we have the interval for z [-3,3]

Using a z-scores table values

Find out the probabilities

For x>3

P(x>3)=0.0013499

For x<-3

P(x<-3)=0.0013499

Adds the two probabilities

P=0.0013499+0.0013499

P=0.0026998

Convert to percentage

P=0.26998%