3. A boiler has four relief valves. The probability that each opens properly is 0.99. (a) Find the probability that at least one opens properly. (b) Find the probability that all four open properly.

An urn contains 3 white balls and 7 red balls. A second urn contains 8 white balls and 2 red balls. An urn is selected, and a ball is randomly drawn from the selected urn. The probability of selecting the first urn is 0.8. If the ball is white, find the probability that the second urn was selected. (Round your answer to three decimal places.)

Susie has three children. Josh has a z-score of 0.87 for his height and David has a z-score of 0.13 for his height. Solve for the probability the Kelley will have a height between her brothers. Positive z-scores: Z 0.0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.0 0.5000 0.5040 0 5080 0 5120 0.5160 0.5199 0.5239 0.5279 0.1 0.5398 0.5438 0.5478 05517 0.5557 0.5596 0.5636 0.5675 0.2 0.5793 0.5832 0.5871 0 5910 0.5948 0.5987 0.6026 0.6064 03 06179 0 6217 0.6255 0. 6293 0.6331 0.6368 0.6406 0. 6443 0.4 0 6554 0.6591 0.6628 0.6664 0.6700 0 6736 0.6772 0.6808 0.5 0.6915 0.695o 0.6985 07019 0.70540.7088 0.7123 07157 0.6 0.7257 0.7291 0.7324 0.7357 0.7389 0.7422 0.7454 0.7486 DELL %24 & 23 8) 4 7 の 10

Ezra buys a bag of cookies that contains 9 chocolate chip cookies, 7 peanut butter cookies, 4 sugar cookies and 4 oatmeal cookies.What is the probability that Ezra reaches in the bag and randomly selects a peanut butter cookie from the bag, eats it, then reaches back in the bag and randomly selects a chocolate chip cookie?  Give your answer as a fraction, or accurate to at least 4 decimal places.

The probability of working on Saturday is 0.52. The probability of working on Sunday is 0.61. The probability of not working on either day is 0.12. What is the probability that you work both days?

Jack has just been given a ten-question multiple choice quiz in history class. Each question has five answers, of which only one is correct. Since Jack has not attended class recently, he does not know any of the answers. Assuming Jack guesses randomly on all ten questions, find the probability that he will answer six or more of the questions correctly and avoid an F.

Cassandra buys a bag of cookies that contains 4 chocolate chip cookies, 8 peanut butter cookies, 6 sugar cookies and 8 oatmeal cookies. What is the probability that Cassandra reaches in the bag and randomly selects a sugar cookie from the bag, eats it, then reaches back in the bag and randomly selects an oatmeal cookie? Give your answer as a fraction, or accurate to at least 4 decimal places.