Find the area, to the nearest thousandth, of the indicated region of the standard normal distribution.

Question

Find the area, to the nearest thousandth, of the indicated region of the standard normal distribution.

The region where z < −0.81

**answer in square unit

Answer 1

z<-.81

a rough calculation would be use z<-1

then apply the empirical rule such that -1<z<1 is 68%

so, (1-.68)/2 = area = .32/2 = .16 = a slightly smaller approximation that the actual area

but to get a more precise solution use z tables or a z calculator

which shows area = .20897

= about .209 rounded to 3 decimal places