Answer :
The response that represents the 86th percentile is 7.884
The response that represents the 55th percentile is 5.69
The response that represents the first percentile 3.85
How to solve for the 86th percentile
mean = 5.4
sd = 2.3
p(X>x) = 0.86
find the value of z using the NORMSINV function in excel with a probability of 0.86
z = 1.080
x = mean + sd*z
= 5.4 + 2.3 * 1.080
= 7.88
How to solve for the 55th percentile
mean = 5.4
sd = 2.3
p(X>x) = 0.55
find the value of z using the NORMSINV function in excel with a probability of 0.55
z = 0.1257
x = mean + sd*z
= 5.4 + 2.3 * 0.1257
= 5.69
c. The first quartile is 25%
z = -0.6745
5.4 + 2.3 * -0.6745
= 5.4-1.551
= 3.85
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