Z=5.714285714285714 because you subtract 0.3z from 0.02z which = 0.28z and then subtract.2 from 1.8 which is 1.6. So then divide 1.6 by 0.28 to find z.
In this question it is given that the promoter first purchased 2 3/4 of ads at first. When one of the concerts got cancelled, then the promoter cancels 1 5/8 pages of ads. It is required to be found the number of pages the promoter is using finally.
Number of pages bought by the concert promoter initially = 2 3/4
= 11/4 pages
Number of pages cancelled by the promoter
after one concert got cancelled = 1 5/8
= 13/8 pages
Then the total number of pages finally used by the promoter = (11/4) - (13/8)
= (44 -13)/8
= 31/8
= 3 7/8 pages
So the total amount of space used for ads by the concert promoter is 3 7/8 pages.
Basically given normal distribution we have to draw the bell curve with standard deviations which should look like(picture below) so draw something like that with center number being mean (3.53) and each positive standard deviation(SD) being + 0.2:
Ex 1 SD is 3.73, 2SD is 3.93, -1SD is 3.33
Now to solve the questions
A. If we know there’s 1000 gas stations and 3.93 is just 2 SD we can just refer to the picture below.
Basically because we’re finding the amount of values that are greater than that it should be percentage to the right of 2 SD. Which is 2.2% or 0.022 Then multiply that by the number of gas station.
So 0.022 * 1000 = 22.
B. This is basically the values between -2SD and 2 SD which is the percentage between them. Add 13.6 *2 + 34.1*2 = 95.2% or 0.952
Now multiply by 1000 * 0.952=952 gas stations.
C. For this one we just find percentage to the left of -1 SD or simpler just subtract half(the right half) and the percentage in 1 SD from 1 to find the remainder which is the value left of -1SD.
1-0.5 - 0.341 = 0.159
Now multiply by 1000 * 0.159 = 159 stations.
Hopefully this helps.