This is a binomial experiment and you'll use the binomial probability distribution because:
- There are two choices for each birth. Either you get a girl or you get a boy. So there are two outcomes to each trial. This is where the "bi" comes from in "binomial" (bi means 2).
- Each birth is independent of any other birth. The probability of getting a girl is the same for each trial. In this case, the probability is p = 1/2 = 0.5 = 50%
- There are fixed number of trials. In this case, there are 5 births so n = 5 is the number of trials.
Since all of those conditions above are met, this means we have a binomial experiment.
Some textbooks may split up item #2 into two parts, but I chose to place them together since they are similar ideas.
A ratio of 5:7 means out of 12 books, 5 are in one category and 7 are in another. (The “category” isn’t specified in this problem.)
So here we’re STARTING with 36 books; we want to find a ratio that is equal to 5:7 and adds up to 36. Well 36 = 3(12), and so if we multiply each number in the ratio by 3 as well, we might get what we want. Doing that gives us 15:21, which adds up to 36 and is equal to 5:7. Boom, that’s the answer.
P.S. Here’s a question you can think about: why do ratios stay the same when you multiply each number by the same amount? (For example, why is 3:1 the same as 6:2?)
pi·18.6^2·123°/360° - 1/2·18.6^2·SIN(123°) = 226.3
38.50 = 100%
31.57 = ?
Multiply: 31.57 x 100 = 3,157
Divide: 3,157 ÷ 38.50 = 82%
100-82= 18% discount
