00:01
We have muo is equals to 30 ,000 and sigma means standard deviation is equals to 9 ,000.
00:10
Therefore, moving to the part a, here let xos, xos the cost.
00:25
So that z score for x is equals to $1 ,000, $15 ,000 is, z equals to x minus ,000.
00:41
New by sigma which is equals to 15 ,000 minus 30 ,000 divided by 9 ,000 which is equals to minus 1 .6667.
00:58
Now, z score 445 ,000 is z score 4x which is 45 ,000 is z score 4x which is 45 ,000 is z score 4x which is 4 ,000.
01:17
Equals to x minus mu by sigma which is equals to 45 ,000 minus 30 ,000 divided by 9 ,000, which is equals to 1 .6667.
01:35
So the proportion of cost are between.
01:39
So the proportion of cost, the proportion of cost are between dollar, 15 ,000 and $45 ,000 is p.
02:07
$115 ,000 greater than x greater than dollar $45 ,000 is equals to p minus 1 .6667 greater than z greater than 1 .6667 which is equals to 0 .90 so the required proportion is the required proportion is the required proportion is the required proportion is 90 .44 % now moving to the part b moving to the part b here the z score for x is equals to z score for x is equals to dollar 50 ,000 is z is equals to x minus mu by sigma which is equals to 50 ,000 minus 30 ,000 divided by 9 ,000 which is equals to 2 .2 .2 .2.
03:42
So the proportion of cost are so the proportion of cost are greater than $50 ,000 is px greater than $50 ,000 is equals to pz greater than $2 .2222 ,000, which is equals to 0 .0331...