please help me with this!!

The centers for disease control say that about 30% of highschool students smoke tobacco (down from a high of 38% in 1997). Suppose you randomly select high-school students to survey tehm on their attitudes toward scenes of smoking in the movies. what's the probability that

A) none of the first 4 students you interview is a smoker?
B) the first smoker is the sixth person you choose?
C) there are no more than 2 smokers among 10 people you choose?


TS Contributor
A) 0.7^4
B) 0.7^5 * 0.3

C) find P(0), P(1), P(2) using the binomial formula (see the post in the Examples section) and add them up
Oh please help me with this!

Statistics from Cornell's Northeast Regional Climate Center indicates that Ithica, NY, gets an average of 35.4" of rain each year, with a standard deviation of 4.2". Assume that a Normal model applies.

A). During what percentage of years does Ithica get more than 40" of rain?

B). Less than how much rain falls in the driest 20% of all years?

C). A Cornell University student is in Ithica for 4 years. Let y "bar" represent the mean amount of rain for those 4 years. Describe the sampling distribution model of this sample mean, y "bar".

D). What's the probability that those 4 years average less than 30" of rain?