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The United States Postal Service reports that 90% of first-class mail within the same city is delivered in two days of the time of mailing. Ten letters are randomly sent to different locations. a. What is the probability that all 10 will arrive within two days? b. What is the probability that exactly 8 will arrive within two days? c. What is the probability that 5 or fewer will arrive within two days? d. What is the mean number of letters that will arrive within two days? e. What is the standard deviation of the number of letters that will arrive within two days?

Respuesta :

a)The probability that all 10 will arrive within two days is 0.3486.

b)  P(x = 8) = 0.1937

c)  P(x=5)= 0.0014

d)  mean = 9

e) Standard deviation = √0.90 = 0.9486

What is Binomial Probability?

The binomial distribution model allows us to compute the probability of observing a specified number of "successes" when the process is repeated a specific number of times and the outcome for a given patient is either a success or a failure.

Given:

p = 90/100 = 0.90

q(probability of success) = 1 - p = 1 - 0.90 = 0.10

n = 10

a)The probability that all 10 will arrive within two days

P(x = 10) = 0.3486

b) P(x = 8) = 0.1937

c) P(x=5)= 0.0014

d) mean = np = 10 × 0.90 = 9

e) Variance = npq = 10 × 0.90 × 0.10 = 0.90

Standard deviation = √0.90 = 0.9486

Learn more about probability here:

https://brainly.com/question/4125528

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