# Statistics

posted by .

70% of the student body of a very large post-scondary institution is female. In a random sample of 12 students, what is the probability that:
a) at most half will be females
b) more than 7 will be females
c) fewer than 3 will be males

I used the Table of Binomial Probabilities:

X P(x) X P(x)
0 .0000 7 .1585
1 .0000 8 .2311
2 .0002 9 .2397
3 .0015 10 .1678
4 .0078 11 .0712
5 .0291 12 .0138
6 .0792

(A) P(at most 1/2 female)=
P(0 or 1 or 2 or 3 or 4 or 5 or 6)
P(x=0)+ P(x=1)+ P(x=2)+ P(x=3)+ P(x=4)+ P(x=5)+ P(x=6)
= .0000+.0000+.0002+.0015+.0078+.0291+.0792= .1178 is this right?

(B) P(more than 7 will be female)=
P(8 or 9 or 10 or 11 or 12)
P(x=8)+ P(x=9)+ P(x=10)+ P(x=11)+ P(x=12)= .2311+.2397+.1678+.0712+.0138= .7236 is this right?

(C) I don't know how to do this one :(

• Statistics -

PS I don't want the answer, for C, I just need to understand how to do the formula. Anyone?

• Statistics -

Anyone? Really need help on how to do this please :)

• IS this right???????? -

OK last time, do I add up P(x) values from the binomial table from 3 through 12 to establish p and then subtract p value from 1 (as I would to get q value) to get answer C)? or would I totally switch the p value from women to men. I would like to keep the integrity of the question as much as possible and keep the p as women, but if I must change then I will.

## Similar Questions

1. ### Satistics

In North American, female adult heights are approximately normal with a mean of 65 inches and a standard deviation of 3.5 inches. a.) If one female is selected at Random, what is the probablility that shes has a height 70 inches or …
2. ### Statistics

A confidence interval was used to estimate the proportion of statistics students that are females. A random sample of 72 statistics students generated the following 90% confidence Interval: (.43, .63). based on the interval above, …
3. ### statistics

A sample of 36 females is taken. What is the probability that the mean height of these women is shorter than 64 inches if we know the height for all American females is N(63,3^2)?
4. ### statistics

calculate the probability that a randomly selected student is a female if they are at most 30 years of age, there are 27 females out of 57 students.
5. ### statistics

suppose 45 students in an organization are male and 55 are female. Ten females and 15 males in the organization are graduating students. What is the probability that a: a.) student chosen at random is male or a graduating student?
6. ### Statistics

In a population, heights of males are normally distributed with u=180 cm and sigma^2=16 cm^2, while the heights of females are normally distributed with u=170 cm and sigma^2= 25 cm^2. a) One random male and one random female are selected …
7. ### statistics

An introductory psychology class has 9 freshman males, 15 freshman females, 8 sophomore males, and 12 sophomore females. If one student is randomly selected from this class, what is the probability of selecting a female?
8. ### Math

Forty-five percent of a large class of students in Statistics are females. Suppose 28 students are selected at random from the class. Use a normal approximation with continuity correction to calculate the probability that the number …
9. ### Probability

suppose 45 students in an organization are male and 55 are female. Ten females and 15 males in the organization are graduating students. What is the probability that a: a.) student chosen at random is male or a graduating student?
10. ### probality

Blue Nile University recently conducted a survey of undergraduate students in order to gather information about the usage of the library. The population for this study included all 4000 undergraduate students enrolled in the university. …

More Similar Questions