00:01
To find the probability that the total number of phone calls kelly makes during an entire year is between 1 ,100 and 1 ,200, we can use the central limit theorem.
00:08
This allows us to approximate the distribution of the sum of a large number of independent random variables with a normal distribution, even if the original variables are not normally distributed.
00:17
We're given that the number of phone calls kelly makes on any given day follows a poisson distribution with a mean of three calls per day.
00:24
There are 12 months each with 30 days, so we'll say that there are 360 days in a year.
00:39
Not just in a normal calendar year, but in the year here in this scenario of 30 days in each given month.
00:52
Since the number of phone calls per day follows a poisson distribution with mean 3, the total number of calls in 360 days will follow a poisson distribution with a mean lambda of 3 times 360, which is 1080.
01:06
And for a poisson distribution with a large mean, the distribution can be approximated by a normal distribution with the same mean and variance...