to qualify for a police academy, candidate must score

Question

to qualify for a police academy, candidates must score in the top 10% on an entry exam. The exam has a μ= 200 and a σ=20 find the lowest possible score to qualify(Assume a normal distribution)

Answer 1

Obtain a z-score chart

http://users.stat.ufl.edu/~athienit/Tables/Ztable.pdf

 

Top 10% has a z-score of 1.218

 

1.218 = (X - 200) / 20

28.571 = X - 200

228.571 = X