The standard normal curve has calculated probabilities given in the table below.

Question

The standard normal curve has calculated probabilities given in the table below. To solve a non standard normal problem follow these steps: Write in P(x lessthanorequalto k) change into a z score draw the standard normal graph, mark the z score and shade it Using normal tables, find the area (probability) One measure of attr4activeness is measured and scored and found to be normally distributed with a mean of 3.93 and a standard deviation of .75 physical attractiveness and self perception Journal of Abnormal Psych a) Find the probability or randomly selecting a subject has an attractiveness measure greater than 2.75 b. Find probability of a subject with a measure greater than 1.90 c. Find the 95 percentile in terms of the problem

Explanation / Answer

mean =3.93 and sd=0.75

a) Z value=(2.75-3.93)/0.75=-1.57

we need to find P(Z>-1.57) which essentially is P(Z<1.57) . From normal distribution table, answer=0.9418

b) Z value=(1.9-3.93)/0.75=-2.71

we need to find P(Z>-2.71) which is P(Z<2.71). from normal distribution table it is 0.9966

c) We need to find P(X<x)=0.95

Z value for 0.95 probability from normal table is 1.65

thus (x-3.93)/0.75=1.65

thus x=1.65*0.75+3.93=5.1675

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