A certain county park was surveyed for plant species ten years ago. At that time

Question

A certain county park was surveyed for plant species ten years ago. At that time there were 40% Smilax, 10% Scotch Broom, 30% Toyon and 20% Poison Oak. Recently, to determine if the distribution of plant species was the same, a sample of 600 plants was taken with the following results. Use a 2% level of significance. Answer questions I through 3. This is a _______ a) Goodness of Fit problem b) Test of Independence The degrees of freedom are a) 5 b) 4 c) 3 d) 2 The distribution of species = a) has changed b) has not changed Data from a random sample of 1000 new car buyers produced the following contingency table. Determine if Car Size and Manufacturer arc independent. Use the contingency table to answer questions 4 through 5. Chi-squared = a) 34.67 b) 45.81 c) 55.87 d) 63.72 Car Size and Manufacturer are independent a) True b) False The marketing manager from Dealer Don's stores wants to know if serving food samples has an effect on the sales of food or are sales independent of whether or not the store gives out food samples. 55 Dealer Don's stores are randomly selected and randomly assigned to either give food samples or not to give food samples. Use a level of significance of 5%. Use the contingency table to answer questions 6 through 7. Chi-squared = a) 12.43 b) 13.35 c) 14.26 d) 15.35 Giving food samples and Daily Sales are independent a) True b) False

Explanation / Answer

1) Here we have given proportions and observe frequescies.

We have to test the distribution of plant species are same.

So it is Goodness of problem tests.

2) Degrees of freedom = 4 - 1 = 3

3)

Categ   p       oi   ei   (oi-ei)^2/ei       alpha            0.02
A   0.4   200   240.00   6.67       d.f (enter manually)   3
B   0.1   80   60.00   6.67       p value                    0.0001
C   0.3   170   180.00   0.56       chi sq critic      9.84
D   0.2   150   120.00   7.50          
Total   1   600   600.00   21.39          

So p-value < 0.02 so.

Conclusion : a) The distribution of species has changed.

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