the average score on a particular exam is determind to be 84.35 with a standard deviation of 7.4. Assume the scores are normally distributed. Applicants with exam scores in the lowest 10% are directed to special training.Find the minimum score required to not be redirected.

Question

amistre64 · Answer

we have a mean, an sd, and an area for consideration; we can use the invNrom function on my ti83 to get the results :)

amistre64 · Answer

74.8665....

amistre64 · Answer

invNorm(.10, 84.35, 7.4) = 74.8665...

anonymous · Answer

is that the same  as doing .10-84.35/7.4 as the equation then finding the z score

amistre64 · Answer

$$z=\frac{x-\bar x}{\sigma}$$
right?

anonymous · Answer

yes

amistre64 · Answer

in this case we algebra it to: $z(\sigma)+\bar x = x$

amistre64 · Answer

the z-score table i have show the area from mean to a tail; the area we want is then 40%; the closest I get to that is (-1.28); so lets see if I did it right :)

amistre64 · Answer

-1.28(7.9) + 84.35 = 74.238

amistre64 · Answer

but the z table aint as accurate as the calculator, but we are close enough

anonymous · Answer

ahh thank you very much!

amistre64 · Answer

youre welcome :)