00:01
During meditation, the reduction in a person's oxygen consumption follows a normal distribution with a mean of 37 .6 cubic centimeters per minute and a standard deviation of 4 .6 cc per minute.
00:15
And for part a, we were asked to find the probability that during a meditation, a person's oxygen consumption is reduced by at least 44 .5 cc per minute.
00:27
So we want the probability that x is greater than or equal to 44 .5.
00:36
If this graph represents the normal distribution of the reduction in oxygen consumption, we have a mean of 37 .6 in the center, 44 .5 is approximately here, and the probability that x is at least 44 .5 is equal to the area under the curve and to the right of 44 .5.
00:59
So the probability is equal to the area of this blue shaded region.
01:03
Now to solve this we first want to express it in terms of the cumulative probability.
01:06
This is equal to 1 minus the probability that x is less than 44 .5.
01:14
If we wish to use a standard normal table to solve this probability, we first standardize the random variable according to this formula.
01:25
In doing so we have 1 minus the probability that z is less than 1 .5.
01:36
So now we can look up z equals 1 .5 in a standard normal table, and we find that that corresponds to a cumulative probability of 0 .9332, and and therefore this probability comes out to 0 .0668.
02:01
So that's the probability of reduction of at least 44 .5 cc.
02:08
Then for part b we want the probability of reduction of at most 35 cc.
02:15
So we want the probability that x is less than or equal to 35.
02:21
Let's solve this one using excel.
02:24
In excel we start the computation with an equal sign...