00:01
So in this question, our first step is to find the z -score.
00:03
So to find the z -score, what we do is do the value of the random variable minus the mean over the standard deviation.
00:17
So we have 13 minus 10 over 2 .4, and this gives us an answer of 1 .25.
00:25
So the probability that z is greater than 1 .25 is going to be found in the table, and we get 0 .1056.
00:42
In part b, we want to find the expected value of t, e of t, and this is equal to 2 times 10 minus 4 times negative 6 plus 4 times negative 11, and we get an answer of negative 32.
01:01
For part c, we want to find the variance.
01:06
So variance of t is equal to 4 times 2 .4 squared plus 16 times 1 .8 squared plus 16 times 0 .7 squared, and we get an answer of 16 .06.
01:27
In part d, we want to find the standard deviation.
01:30
So that's going to be the square root of the variance, which is 4 .008.
01:42
In part e, we want to find the probability that t is within 0 .7 standard deviation...