00:02
We'd like to find these different probabilities.
00:06
To solve these problems, we want to use our binomial distribution.
00:13
This describes the number of successes and a fixed number of independent for newly trials.
00:19
We're given our number of trials as 128, and our probability of a success as 0 .40.
00:26
For a binomial distribution, we can calculate the mean and a standard deviation.
00:33
Mean is n times p or 51 .2 and our standard deviation is n p times 1 minus p which is 5 .49.
00:46
Now let's solve.
00:47
We want the probability that half or more of these claims have been padded.
00:54
We first want to convert this to a z score, which is x minus mu over sigma.
00:59
We have 64 minus 50.
01:02
1 .2 divided by 5 .49 to give us 2 .33.
01:09
Then we look at our standard normal distribution table.
01:12
We want the probability that z is greater than 2 .33.
01:17
That gives us about 0 .99%.
01:22
So this is our probability for a.
01:26
What about the probability that fewer than 45 have been padded? we first want to convert this to a z score...