Assume thatxhas a normal distribution with the specified mean and standard deviation. Find the indicated probability. (Enter a number. Round your answer to four decimal places.)

=20;=3.8

P(x30)

Sketch the area under the standard normal curve over the indicated interval and find the specified area. (Enter a number. Round your answer to four decimal places.)

The area betweenz=0.33andz=1.84is

Consider anxdistributionwith standard deviation=42. (For each answer, enter an exact number.)

(a)If specifications for a research project require the standard error of the - corresponding x distributionto be3, how large does the sample size need to be? 

n=________

(b)If specifications for a research project require the standard error of the - correspondingx distributionto be 1, how large does the sample size need to be? n= 

the dash is supposed to be directly over the x not sure how to type that.