Question 1197884
Normal Distribution: µ = 420 and σ = 80  
Using a hand held TI or similarly an inexpensive calculator like an Casio fx-115 ES plus
a. P( 400 ≤ x ≤ 480) = normcdf(400,480,420,80) = .3721
b. Invnorm(.95) = 1.645
 x = 1.645*80 + 420 = 551.6  
552 the minimum test score needed in order to be in the top 5 % of all people taking the test