Question

USING EXCEL

1.         For the most part, our multiple-choice quiz (and Evaluation) questions have four possible answers. (Yes, I know. I throw in an extra answer now and then!)   Suppose you come to a quiz hoping to guess your way through to a decent grade. Find the probability of guessing at least 5 out of the 10 multiple-choice questions correctly, using BINOM.DIST with pdf (i.e., summing each of the individual probabilities of 5, 6, ….., 9, 10), and then with cdf (i.e., taking the complement of one of the cdf values.) Round (final answer only) to 3 digits. Do not round your intermediate answers.

Make sure you label your two methods, “Method 1” and “Method 2” so that they serve as headers for the work you display beneath each.

So would you consider this event likely or unlikely to occur? Explain your answer.

Review: using BINOM.DIST(x, n, p, false) is the pdf function, since the false tells you that this is the probability for only x successes out of n trials with a probability, p, on any trial.

For example, if you’re interested in computing P(X=10) for n = 20, p = .5, then enter

“BINOM.DIST(10,20,5, FALSE)”

However, if you wish to calculate the P(X ≤ 10), enter

“BINOM.DIST(10,20,.5,TRUE)”, since “TRUE” indicates that you wish Excel to give the cumulative probability, that is the sum of the following probabilities:

P(X=0)+P(X=1)+P(X=2)+P(X=3)+P(X=4)+…+P(X=10); whereas inserting

“FALSE” gives you only P(X=10).

2.         Now answer the same questions in (a), assuming that each of our weekly quiz questions has 5 answers instead of 4. Again, use both methods, making sure to label your work “Method 1” and “Method 2”.

Answer 1