Which of these expressions entered into a graphing calculator will return the probability that 450 or fewer heads come up when flipping a coin 500 times?

A. binomcdf( 450, 0.5, 500)
B. binomcdf( 500, 0.5, 450)
C. binomcdf( 450, 500, 0.5)
D. binomcdf( 500, 450, 0.5)

Question

Which of these expressions entered into a graphing calculator will return the probability that 450 or fewer heads come up when flipping a coin 500 times?

A. binomcdf( 450, 0.5, 500)
B. binomcdf( 500, 0.5, 450)
C. binomcdf( 450, 500, 0.5)
D. binomcdf( 500, 450, 0.5)

perl · Answer

we want P ( X <= 450) , and this will use a binomial cdf
the parameters of a binomcdf is 

binomcdf( total trials, probability, up to some number)

hockeychick23 · Answer

oh ok so it would be binomcdf( 500, 0.5, 450) so the end result would be 450?

perl · Answer

the end result will be a decimal

hockeychick23 · Answer

oh why?

perl · Answer

probability is always a decimal between 0 and 1

perl · Answer

and cumulative probability is at most 1

perl · Answer

the cumulative result is .99999999...

hockeychick23 · Answer

ohhh ok so its d then because its the total trials with the probability last gotcha, thanks!

perl · Answer

no its b )

hockeychick23 · Answer

oh i thought you said the end result would be a decimal