Of all the trees planted last year by a landscaping firm, 10% died within a mont
ID: 3382109 • Letter: O
Question
Of all the trees planted last year by a landscaping firm, 10% died within a month. Suppose a new landscaping firm is hired to plannt 15 new trees. let X denote the number of tress planted (out of 15) that died.
a. what values of X suggest that the new landscaping company has a lower failure rate?
b. what values of X are consistent with the previous landscaping company's failure rate?
c. what values of X indicate that the new landscaping company has a higher failure rate than the previous contractor?
Explanation / Answer
Let Y be the number of trees died out of 15 planted by the old firm.
Then Y~Bin(15,0.1)
Expected number of dead trees = E(Y) = 15 *0.1 = 1.5
(a)
X=0,1 suggest that the new landscaping company has a lower failure rate.
(b)
X=1,2 are consistent with the previous landscaping company's failure rate.
(c)
X=2,3,4,...,15 indicate that the new landscaping company has a higher failure rate than the previous contractor.
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