What is the area to the left of z= -1.97 is

Question

The area to the left z= - 1.96 is

Answer 1

to the left of z=-1.96 is .00250

= 0.25 % probability

to the left of z=-1.97 is 0.00244

= 0.244 % probability

that's from looking at z tables

you could just use the empirical rule 68-95-99 or more precisely 68.3-95.5-99.7 percent for 1,2 and 3 standard deviations from the mean

1.96 and 1.97 are almost 2, so use 95 or 95.5%

95% means 5% beyond 2 standard deviations. Divide by 2 to get 2.5%

convert to decimal: 0.0250 which is the same as for the z table for 1.96