Download 6.3 Calculator Examples

1.11.2016
Using our Calculator for Binomial
Random Variables
• “choose” notation (binomial coefficient)
11
–
5
•
Would be read as “11 choose 5”
11!
5! 11−5 !
= 462
– You can use the nCr function on your calculator
• 11𝐶5 = 462
• Press 11, then nCr, then 5
Using our Calculator for Binomial
Random Variables
• Our calculator can also directly calculate binomial
probabilities
• Binompdf(n,p,k) computes the probability that X=k
• Binomcdf(n,p,k) computes the probability that X≤k
– Remember, n is the number of trials
– P is the probability of success in any given trial
Let’s Try an Example
• On average, a football team wins 40% of their
games. Over the course of a 12-game season,
what is the probability that they win exactly 7
games?
Let’s Try an Example
• On average, a football team wins 40% of their
games. Over the course of a 12-game season,
what is the probability that they win exactly 7
games?
• Binompdf(12, .4, 7) = .1009
• What about winning 7 OR MORE games?
Let’s Try an Example
• On average, a football team wins 40% of their
games. Over the course of a 12-game season,
what is the probability that they win exactly 7
games?
• What about winning 7 OR MORE games?
– 1- Binomcdf(12, .4, 6)= .1582
Using our Calculator for Geometric
Random Variables
• Our calculator can directly calculate geometric
probabilities as well
• Geometpdf(p,k) calculates the probability that
Y=k
• Geometcdf(p,k) calculates the probability that
Y≤k
Another Example
• Let’s look at a tennis player who makes 44% of
her first serves
• What is the probability that it takes her
exactly 3 serves to make one?
Another Example
• Let’s look at a tennis player who makes 44% of
her first serves
• What is the probability that it takes her
exactly 3 serves to make one?
– Geometpdf(.44, 3)= .138
• What is the probability that it takes her less
than 5 tries to make a serve in?
Another Example
• Let’s look at a tennis player who makes 44% of
her first serves
• What is the probability that it takes her 5 or
fewer tries to make a serve in?
– Geomeetcdf(.44, 5) = .902