## anonymous one year ago ......

1. jtvatsim

Sorry, I'm trying to find a good graph, I was busy editing the picture to work with this problem. :)

2. jtvatsim

Alright, this will require some explanation, but you can see the graph attached. This shows the diagram of a normal distribution. We will use this to solve the problem.

3. jtvatsim

The white percentages show the number of people between standard deviations. For example, 34.1% of people are between 0 and 1 standard deviation (the weird $\sigma$ symbol stands for standard deviation)

4. jtvatsim

The red percentages are the ones that we care about in this problem. They show the total percentages. So, for example, at +1 standard deviation 84% of people are to the left of that point.

5. jtvatsim

From the question, we are told the following: mean = 12.89 standard deviation = 1.95 Marcus's score = 13.7 People who get certificates score better than 98% of people.

6. jtvatsim

The reason this problem seems hard is because we can't tell if 13.7 is better than 98% of people. If we knew that 13.7 was better than 98%, then Marcus should get a certificate. However, if 13.7 is worse than 98%, then Marcus should not get a certificate. We need a way to turn the 98% into a score for us to compare.

7. jtvatsim

Let me stop for a moment and give you a chance to ask any questions you have. You are probably still a little confused on the diagram I posted, but I'll explain how that comes in, in just a moment. The biggest thing is are you ok with the fact that we need to figure out what 98% actually means?

8. anonymous

yes, i probably could

9. sohailiftikhar

waite i'm looking the work of jv

10. anonymous

yes, i probably could

11. sohailiftikhar

so here we are given the situation that certificate will only give to the top 2% of those people who gave test .

12. sohailiftikhar

so if marcus didnt receive a certificate that's means he is not in that top 2% people even he score well ..understand ?

13. sohailiftikhar

we have to give a certificate only 2% people so we will take the top 2% means with higher score

14. sohailiftikhar

no he didn't receive the certificate because he was not in the toppers list

15. sohailiftikhar

this is given in statement . take a look that what they asked

16. sohailiftikhar

yes

17. sohailiftikhar

that's what i'm saying that he can't get enough score to get in 2% of ppl whos score is higher means toppers

18. sohailiftikhar

ok here is a example there are 20 seats in the company and they said that only 20 ppl can get job but for the minimum job score is 33 out of 100

19. sohailiftikhar

so one candidate scored 50 but he didn't get job ..why ?

20. sohailiftikhar

yes

21. sohailiftikhar

this what happened here ..they said they only give 2% of certificates and when they got filled marcus didn't get certificate because didn't get high score to be in that 2% of ppls

22. sohailiftikhar

consider these 2% are those whos score is 20,21and so on so this is higher than marcus .. get it now ?

23. sohailiftikhar

yes he didn't get the high score to beat the others

24. sohailiftikhar

so ? i'm going now

25. sohailiftikhar

it's simple you can say that there 2% of ppl who scored higher than marcus and we only have to give certificate of 2% ppl so he can't get certificate..

26. sohailiftikhar

i mean i'm going to offline now