week 5 math

Week 4 Binomial distribution illustrated by Bethany Mueller.html

Week 5 - Example 6

Here is an example by the steps

Binomial Distribution in Excel

For binomial distribution exercise, we use the binom.dist command in Excel.

(For Excel 2007 and older, use the command “binomdist.”)

Note: We use "true" if we're calculating a cumulative probability. We use "false" to calculate the exact probability. In a nutshell, type “TRUE” when you have a “less than” probability (like if the exercise has a strictly “<“ sign) and type “FALSE” when you have a strictly “equals” probability.

Example: A recent survey found that 17% of adults dislike Marshmallow Fluff. Suppose you randomly select four adults and ask them if they like Marshmallow Fluff.

1. What is the probability that exactly two of them dislike Marshmallow Fluff?
2. What is the probability that fewer than two of them dislike Marshmallow Fluff?
3. What is the probability that at least two of them dislike Marshmallow Fluff?
4. What is the probability that 2 or fewer dislike Marshmallow Fluff?

 

Part a: n = 4, P = 0.17 and x = 2 (we use x = 2 and "FALSE" because we're calculating the exact probability for "equals 2")

 

Part b: n = 4, P = 0.17 and x < 2 (“fewer than two” means zero or one so we use x = 1 and "TRUE" because we're adding the probabilities of 0 and 1)

 

Part c: n = 4, P = 0.17 and x >= 2 (“at least two” means two, three, or four; note that this is the compliment of part b)

 

Part d: n = 4, P = 0.17 and x <= 2 (“two or fewer” means zero, one or two so we use x = 2 and "TRUE" because we're adding the probabilities of 0, 1, and 2)