Alegebra
posted by Samantha .
A physical fitness association is including the mile run in its secondaryschool fitness test. The time for this event for boys in secondary school is known to possess a normal distribution with a mean of 450 seconds and a standard deviation of 50 seconds. Find the probability that a randomly selected boy in secondary school can run the mile in less than 335 seconds.
Is the answer 0.0107? Anyone please

can some one please help me!!!

You are given the normal model N(450, 50)
Find the z score for 335 seconds.
z = (xu)/s
where u = mu and s = sigma.
z = (335450)/50
z = 2.3
Now use the normal cumulative distribution function on a calculator or program to find the P(z<2.3)
normalCDF(99,2.3) = .0107 
Marth this are my choices
A) 0.9893
B) 0.0107
C) 0.4893
D) 0.5107
So I'm assuming it's letter B? correct 
Dahhhh lol