00:01
8 .5 % of bridges in a large state are structurally deficient.
00:05
We have a sample of 100 bridges in this state.
00:09
So the probability each is deficient will be 8 .5%, or 0 .085 in decimal form.
00:16
We don't want to use percentages because we're going to do a calculation, and percentages do not play well with calculations.
00:22
What is the probability that 6 out of these 100 are deficient? so this is a binomial distribution.
00:31
It meets all of the criteria.
00:33
N independent trials, two outcomes for each, structurally deficient or not, same probability p that each is.
00:40
And i'm going to use my ti -84 following the binomial formula for ability to exactly x being deficient.
00:48
Is n choose x, which i'll write as this since i'm using my calculator, multiplied by p to the x and 1 minus p to the n minus x.
01:00
So we want x to be equal to 6.
01:03
Although there is actually a binomial function, it's just called binom .pdf...