Question

Determine the following areas under the standard normal (z) curve: (Round your answers to four decimal places.) (a) To the left of −1.29 (b) To the right of 1.29 (c) Between −1 and 1 (d) To the left of 0 (e) To the right of −6 (f) Between −1.7 and 2.5 (g) To the left of 0.23

Answer 1

a) 0.985

b) 0.0985

c) 0.6826

d) 0,5

e) 1

f) 0.9492

g) 0.5910

Explanation:

a) Directly from z table: The area to the left of -1.29 is 0.985

b) To the right of 1.29 We get from z table the value of 0.9015 this value is the area from the point 1.29 up to the left tail, so we have to subtract 1 - 0.9015 and get 0.0985 (the area from the point 1.29 to the left)

c) Are between -1 and 1 . We find in z table values for 1 ( 0.8413 ) and for -1 ( 0.1587) ( this last area is already included in the area of the point 1 so again we must subtract

0.8413 - 0.1587 = 0.6826

d) To the left of 0 the aea is 0,5

e) To the right of -6 is of course 1

f) Between -1.7 and 2.5 . we find from z table the values

-1.7 ⇒ 0.0446 (this area is included in the area of the point 2.5) and for 2.5 ⇒ 0.9938

Then area between -1.7 and 2.5 is : 0.9492

g) Area to the left of 0.23 is directly fom z table : 0.5910