00:03
So we know that the battery life follows a normal distribution with the mean of four years and a senior deviation of three.
00:09
And we're going to know what's the probability that the battery life will last longer than four and a half years.
00:15
So since it follows a normal distribution, we're going to use our normal cdf.
00:18
Our lower bound is 4 .5.
00:20
Our upper bound is a really, really, really large number.
00:23
Our mean is 4 and standard deviation is 3.
00:25
And this gives us a probability of 0 .0478.
00:30
Next, we want to know what's the probability the battery life will last more than 3 .75 years.
00:35
So again, we're going to use normal cdf, our lower bound 3 .75, our upper bound, just a really, really, really large number.
00:42
Our mean forest unionivation three, and this is going to give us 0 .7977...