Copy of HNozProbability 9146910917 $- Insert Draw Page Layout Formulas Data Revi
ID: 2928351 • Letter: C
Question
Copy of HNozProbability 9146910917 $- Insert Draw Page Layout Formulas Data Review View Tell me what Home Merge & Center . : $-96 , l..g B 1 u.lw.16-A-| ormat Pannter 873 54 3. Exercise 3 55 The mean and standard deviation (kg/ha) of wheat yiekd two different sols are given in the table below 57 mean std dev soil A soil B 300050 4000 000 60 61 62 a. What are the mean and variance of the differences between sample averages 63 (average of B average of A) when independent samples of size 9 are taken from fields 64 , in soil A and samples of size 16 are taken from fields in soil B? 65 9 16 rB mean- 1000 This is the mean of the differences between averages 45000 This is the variance of the difference between averages. 67 68 69 701b What is the central range of average yields thatis expected to contain 90% of the 71 sample averages from fields in soil A? 18] 72 73 variance alpha no of tails lower extreme - Exercises DOLLExplanation / Answer
Yes i believe your ans for A is correct
for b as you asked
As you know that we are measuring the distnace from the mean in both the directions and so it's a 2 tail test.
So ans for tails = 2
now the formula for the lower tail will be ., z=(Xbar-mu)/sigma
here we need to find Xbar and we have mu=3000 and sigma=450 given but for cal Z value the excel has a formula named =NORM.INV(0.05,0,1) which says z value at 5% with mean 0 and sd 1 which you can use
So the ans will be for lower tail (left side 5% area)= "=NORM.INV(0.05,0,1)*C58 + B58" which will be
2259.816
And the same for upper tail (right side 5% area)="=NORM.INV(0.95,0,1)*C58 + B58" which will be
3740.184
Even you can use the same logic to ans the c question as well. Remember to put .025 and 0.975 inplace of 0.5 and 0.95 in the norm.inv function since it's @5% alpha
i hope you understand by doing =NORM.INV(0.95,0,1) I'm getting the Z value at 95% of the area of the normal distribution
Hope this has helped you in understanding the problem . Pls upvote the ans if it has really helped you. Good Luck!!
2259.816