SOLUTION: Scores for a particular standardized test are normally distributed with a mean of 80 and a standard deviation of 14 . Find the probability that a randomly chosen score is (i) N

Algebra ->  Probability-and-statistics -> SOLUTION: Scores for a particular standardized test are normally distributed with a mean of 80 and a standard deviation of 14 . Find the probability that a randomly chosen score is (i) N      Log On


   

Question 1197678: Scores for a particular standardized test are normally distributed with a mean of 80 and
a standard deviation of 14 . Find the probability that a randomly chosen score is
(i) No greater than 70
(ii) At least 95
(iii) Between 70 and 95
(iv) A student was told that her percentile score on this exam is 72% . Approximately what
is her raw score?

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi
Using TI or similarly an inexpensive calculator like an Casio fx-115 ES plus

Recommend Using stattrek.com to check Your results until 
You are comfortable Using Your Calculator.

Normal Distribution: µ = 80 and σ = 14

P(x ≤ 70) = normcdf( -9999, 70, 80, 14) = .2375

P( x ≥  95) = normcdf(95, 9999, 80, 14) = .142

P( 70 ≤ x ≤ 95) =  normcdf(70, 95, 80, 14) = .4148

Percentile score 72%:  z = Invnorm(.72) = .5828
blue%28sigma%29%2Az+%2B+mu=+blue+%28x%29  x = 14(.5828) + 80 = 88 rounded 

Wish You the Best in your Studies.