The probability that Z is less than 1.13

Question

can someone help me with this problem

 

Answer 1

The z score represents a value on the standard normal distribution. To find the probability of being greater or less than a certain value, we consult a z-chart or use a calculator to find the area under the probability distribution curve to the right or left of the value given.

 

The chart I have specifies values of the area to the left of the z-score that I look up. For a z-score of 1.13, my chart tells me the area to the left of (which is the probability that a value is less than) 1.13 is 0.8708.

 

If you wanted the probability of more than 1.13, you'd subtract this from 1. 1-0.8708 = 0.1292. On the TI-83/84 line of calculators, you can find this under the STAT menu and use normalcdf(-9999, 1.13).