The PDF for the wait time (denoted by the random variable X) is
where λ = 1/75. We want to find Pr[X > 70 | X ≥ 40]. Pierre has already been waiting for 40 min, so if he waits another 30 min he will have waited for a total of 70 min.
By definition of conditional probability,
Pr[X > 70 | X ≥ 40] = Pr[X > 70 and X ≥ 40] / Pr[X ≥ 40]
If X > 70, then automatically X ≥ 40 is satisified, so the right side reduces to
Pr[X > 70 | X ≥ 40] = Pr[X > 70] / Pr[X ≥ 40]
Use the PDF or CDF to find the remaining probabilities. For instance, using the PDF,
Or, using the CDF,
Similarly, you'll find that Pr[X ≥ 40] ≈ 0.5866.
It follows that
Pr[X > 70 | X ≥ 40] ≈ 0.3932 / 0.5866 ≈ 0.6703
B) 8:45am - 5:15pm
Hope this answers your question!
The answer would be 1.
This is due to 5+8 equaling 13.
Then if you subtract 1 from 14 you also get 13.
Answer:
7.5
Step-by-step explanation:
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