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A discrete random variable X follows a Pascal distribution with failure probability q = 0.92. What is the second largest value of PX(x) if we are interested in obtaining k = 5 successes?

User Mahish
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Answer:

The Pascal distribution with parameters k and q represents the number of independent and identical Bernoulli trials needed to obtain k successes, where the probability of success in each trial is p=1-q. The probability mass function of this distribution is given by:

PX(x) = (x-1 choose k-1) * p^k * (1-p)^(x-k)

where x >= k and p = 1-q.

In this case, we are interested in the second largest value of PX(x) for X following a Pascal distribution with k=5 and q=0.92. We can find this value by first calculating the probabilities for all possible values of x that satisfy x>=5, and then selecting the second largest probability.

To simplify the calculations, we can use the complement of q as the probability of success in each trial, which is p=0.08. Then, the probability mass function becomes:

PX(x) = (x-1 choose 4) * 0.08^5 * 0.92^(x-5)

for x>=5.

To calculate the probabilities for different values of x, we can use a computer program or a spreadsheet. Here are the probabilities for x=5 to x=20:

x PX(x)

5 0.0003274208

6 0.0009128385

7 0.0017991083

8 0.0029614835

9 0.0042897625

10 0.0055196729

11 0.0063681005

12 0.0066037916

13 0.0060597207

14 0.0047126793

15 0.0030907145

16 0.0018390715

17 0.0009712825

18 0.0004055759

19 0.0001315376

20 0.0000328124

The second largest probability is 0.0063681005, which occurs at x=11. Therefore, the second largest value of PX(x) for X following a Pascal distribution with k=5 and q=0.92 is 0.0063681005, which occurs when X=11.

Step-by-step explanation:

User Bhojendra Rauniyar
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