## mariomintchev 3 years ago stats help needed...

1. mariomintchev

2. mariomintchev

i need help with part A

3. mariomintchev

i dont know what to do after i get the z-score... which is -0.966 (when rounded)

4. mariomintchev

@estudier @myininaya @phi @sasogeek @Tyler1992

5. mariomintchev

@bahrom7893

6. mariomintchev

like what is the next step? i have the zscore and i have the graph drawn out (68-95-99.7)

7. bahrom7893

You look it up in the z-table. Sorry I'm bad at stat, hang around while help comes.

8. mariomintchev

@ash2326 @Jemurray3

9. bahrom7893

@amistre64 @satellite73

10. bahrom7893

@Libniz

11. phi

look in you z table for the area above -0.966 std dev. it looks like about 83 %

12. mariomintchev

can you show me the work? im confused on the last steps

13. mariomintchev

like how would i solve it without using Excel or something like that

14. phi

You would use a z-table or calculator Do you use a table ?

15. mariomintchev

i dont know what a z table is to be frank

16. phi

Here is a site that does the conversion http://www.tutor-homework.com/statistics_tables/statistics_tables.html How are you doing these problems?

17. mariomintchev

this is the first one like this on my hw

18. phi

19. phi

but to do a) select standard distribution (the first one shown) right tail type in -0.966 for z and have it calculate the area under the curve to the right of that z score. that is the chance the weight is above this z score

20. mariomintchev

any way this can be done on a graphing calc rather than on this site?

21. phi

if it knows about normal distributions (do they?) otherwise http://en.wikipedia.org/wiki/Normal_distribution#Numerical_approximations_for_the_normal_CDF is a (messy) way

22. REMAINDER

using normal since ur z score is -0.966 round to 2 decimal u'll have -0.97 it means u'll have P(z>=-0.97) because it is over 1050 u'll have 1-P(Z<=-0.97) on the z table -0.97 it hase the probability of 0.1660 now 1-(0.1660) 0.834 wich by conclusion is 83.4%

23. REMAINDER

do u get it?

24. mariomintchev

yeah i get everything except the part where i get the 0.1660. i dont know how to get it without using the site Phi gave me above. ^^^

25. mariomintchev
26. REMAINDER

check this tables

27. REMAINDER

do u see -0.97 ?

28. mariomintchev

yes i get that by doing the formula for z score and rounding

29. REMAINDER

do u see the value that correspond to it ?

30. mariomintchev

not really no. i dont get how that part works.

31. REMAINDER

|dw:1348601547745:dw| the deshes represents some numbers on the table ;right

32. mariomintchev

yeah. i just dont know how i get this table to see the probability.

33. REMAINDER

to find this 0.1660 take -0.9 ignore negative (meaning u gonna take 0.9)then add it to 0.07 wich will give positive 0.97 from there where -0.9 intersects 0.07 is ypur probability

34. REMAINDER

do u follow?

35. mariomintchev

yes i get that. i dont know how to get that table though.

36. Mahlatse1

what do you mean you dont know how to get the table?

37. REMAINDER

do u mean u don't have the table

38. mariomintchev

yes

39. REMAINDER

check the attechement skbmt it has tables

40. Mahlatse1

41. REMAINDER

@mariomintchev mahlatse posted them

42. mariomintchev

thanks

43. REMAINDER

u r welcome