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Gravel is graded by how fine the stones are. For a particular grade of gravel, there are 26 stones with a diameter of 0.75 inches or greater per one cubic yard of gravel, on average. (a) We would like to determine the probability of finding at most two stones with a diameter of 0.75 inches or greater in one cubic foot of the same gravel. Which of the following is the correct probability statement? P(x < 2) PX S2) P(x > 2) P(X22) (b) We would like to determine the probability of finding at most two stones with a diameter of 0.75 inches or greater in one cubic foot of the same gravel. (1 cubic yard = 27 cubic feet. Round your answer to three decimal places.) 0.960 HE -0.963 27

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Answer:

p(x≤2)

0.926

Explanation:

1. The probability of getting 2 stones with a diameter of 0.75 or greater can be given as

P(x≤2)

2. We have λ = 26/27

= 0.963 per cubic foot

We use the poisson distribution here;

P(x) = e^-λ(Rλ)^x/x!

P(x≤2) = p(x=0)+p(x=1)+p(x=2)

= e^-0.963 + e^-0.963(0.963) + e^-0.963(0.963)²/2!

= 0.3817+0.3675+0.1769

= 0.926

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