# (Solved): There Are Seven Photocopiers, And Three Of These Photocopiers Are Defective. The Buyer Begins To Tes...

There are seven photocopiers, and three of these photocopiers are defective. The buyer begins to test them one at a time to figure out which three are defective.

a. What is the probability that the first defective photocopier is found on the fifth test?

b. What is the probability that the second defective photocopier is found on the fifth test?

c. What is the probability that the third defective photocopier is found on the fifth test?

d. What is the probability that no more than five tests are needed to find the three defective photocopiers?

e. Given that exactly one of the defective photocopiers was found within the first three tests, what is the probability that the other two defective photocopiers are found within the next three tests?

f. Given that exactly two of the defective photocopiers were found within the first three tests, what is the probability the last defective photocopier is found within the next two tests?

g. Given that exactly two of the defective photocopiers were found within the tests 1, 3, 5, what is the probability the other defective photocopier was found on tests 6 or 7?

h. Given the last defective photocopier was found within the last two tests, what is the probability that the first two defective photocopiers were found within the first three tests?