What is the area under the normal curve between z = 1.0 and z = 2.0? A. 1.0000 B. 0.4772 C. 0.1359 D. 0.7408

1sd = 65% 2sd = 95% 30% / 2 ~ 15% C. 0.1359

What is the probability that a value of 30 or more will be observed from a normal distribution with a mean of 15 and standard deviation of 25? A. 72.6% B. 50% C. 27.4% D. 60%

gotta be C by default, no?

P(Z>(30-15)/25) P(Z>0.6) 1-P(Z<0.6) don’t have a z-table so i can’t answer

tvPM Wrote: ------------------------------------------------------- > gotta be C by default, no? brain is always better than laborious calculation !!! btw sharp: can u justify as I don’t understand ur way. ur ans is correct

whos answer is correct?

ok sharp !!

my way uses regular probability concepts and a z -table though on the exam for a question like this i’d probably draw a normal curve with the sd=1 marked down and try to derive the answer that is most correct

yeah I follow your method. I just figure if you are asking somethin on one side of the mean like that it has to be less than a 50% chance since the mean is at 50/50 for a normal distribution like it states. Therefore the only option was C.