Answer: μ = 647.4
Step-by-step explanation:
The question says
"A psychologist has designed a questionnaire to measure individuals' aggressiveness. suppose that the scores on the questionnaire are normally distributed with a standard deviation of . suppose also that exactly of the scores exceed"
And we are told to find the mean of the distribution scores.
Given mean μ = ?
we have from standard normal table that
P(Z > 1.282) = 0.1
Therefore the given Z score of a score of 750 is given thus 1.282.
the z score is given:
x - μ / α = 1.282
750 - μ / 80 = 1.282
Therefore μ = (750 - 80)*1.282 = 647.4
So we have that μ = 647.4
cheers i hope this helped !!!