Suppose 65% of Princeton students like World Coffee better than Hoagie Haven. We selected a random sample of 20 students, and asked them which they prefer. What is the probability that more than 18 students said “World Coffee”? Write R code to compute the actual probability.
Hint:
We solved a very similar problem in class on April 2 with coin tosses. Each student answer can be thought of as being like a coin toss. Decide whether you want “Heads” to represent HH or WC, and then solve the problem using
pbinom
, just like we did in class.
In class, we saw several ways to compute the cumulative probability for the binomial distribution: we used pbinom
; we summed up the outputs of dbinom
; we also generated a large sample using rbinom
, and then computed the proportion of the generated numbers that was under a certain threshold.
Write a function named MyPbinom1
, which works just like pbinom
. You may use dbinom
but not rbinom
in the function you write.
Write a function named MyPbinom2
, which works just like pbinom
. You may use rbinom
but not dbinom
in the function you write.