The probability that a person will subscribe to Statistics Monthly is 48%. Find the probability that out of a group of seven, at least one person subscribes.

There are charts as well – but only for some probabilities so you need to know the formula.

MORE BINOMIAL USING CALCULATORSection 6.3B

Using the calculator to find binomial probabilities.• To find exactly 1 probability:

binompdf(n, p, x)

Press: 2nd Distribution

0 binompdf(n,p,x)

n – for number of trials

p – for given percent

x - # we want

A tourist bureau for a western state conducted a study, which showed that 65% of the people who seek information about the state actually come for a visit. The office receives 15 requests for information on the state. Find the probability that exactly 10 visit.

• Binompdf(15, 0.65, 10)

• You should get 0.2123 or 21.2%

Remember: PDF is for exactly

To accumulate probabilities – adding more than one- we use binomcdf.

• It accumulates starting with x = 0 up to the value you want.

• It’s under 2nd distribution

A binomcdf (n, p, x)

A survey found that 30% of teens get spending money from part time jobs. If 5 teens are selected at random find the probability that at most 3 of them have part time jobs.

x p(x)

0 0.16807

1 0.36015

2 0.3087

3 0.1323

4 0.02835

5 0.00243

0.96922

On the calculator:

Binomcdf(5, 0.30,3)

A survey found that 30% of teens get spending money from part time jobs. If 5 teens are selected at random find the probability that at least 3 of them have part time jobs.

x p(x)

0 0.16807

1 0.36015

2 0.3087

3 0.1323

4 0.02835

5 0.00243

0.16308

On the calculator:

Binomcdf(5, 0.30,2)= 0.83692

1 - Binomcdf(5, 0.30,2) = 0.16308

To do the bottom of the list:• You accumulate the top part of the distribution.

• Subtract from 1.

A survey found that 30% of teens get spending money from part time jobs. If 5 teens are selected at random find the probability that more than 3 of them have part time jobs.

x p(x)

0 0.16807

1 0.36015

2 0.3087

3 0.1323

4 0.02835

5 0.00243

0.03078

On the calculator:

Binomcdf(5, 0.30,2)= 0.96922

1 - Binomcdf(5, 0.30,3) = 0.03078

Tim did not study for his quiz with 5 multiple choice (A, B, C, D) questions. Hint: Probability of correct choice is ¼ = 0.25!• What is the probability that he got exactly 3 correct?

• What is the probability that he got at most 2 correct?

• What is the probability that he got more than 3 correct?

A certain type of penicillin will cause a skin rash in 35% of the patients receiving it.

• If the penicillin is given to a random sample of 15 patients what is the probability that at least 7 will have a skin rash?

• If it is given to a random sample of 9 patients, what is the probability that at least one will have a skin rash?

• If it is given to a random sample of 12 patients, what is the probability that exactly 5 will have a skin rash?

Homework

*Worksheet