# Question: A stock brokerage has four computers that are used for

A stock brokerage has four computers that are used for making trades on the New York Stock Exchange. The probability that a computer fails on any single day is 0.005. Failures occur independently. Any failed computers are repaired after the exchange closes, so each day can be considered an independent trial.

(a) What is the probability that all four computers fail on one day?

(b) What is the probability that at least one computer fails on a day?

(c) What is the mean number of days until a specific computer fails?

(a) What is the probability that all four computers fail on one day?

(b) What is the probability that at least one computer fails on a day?

(c) What is the mean number of days until a specific computer fails?

## Relevant Questions

A computer system uses passwords consisting of the lowercase letters (a–z) and the integers (0–9). There are 10,000 users with unique passwords. A hacker randomly selects (with replacement) passwords in an attempt to ...Glass bottles are formed by pouring molten glass into a mold. The molten glass is prepared in a furnace lined with firebrick. As the firebrick wears, small pieces of brick are mixed into the molten glass and finally appear ...A quality characteristic of a product is normally distributed with mean µ and standard deviation . Specifications on the characteristic are 6 x 8. A unit that falls within specifications on this quality ...A new process has been developed for applying photoresist to 125-mm silicon wafers used in manufacturing integrated circuits. Ten wafers were tested, and the following photoresist thickness measurements (in angstromx × ...A random sample of 200 printed circuit boards contains 18 defective or nonconforming units. Estimate the process fraction nonconforming. (a) Test the hypothesis that the true fraction nonconforming in this process is 0.10. ...Post your question