Question 6
In a box of 11 parts, 4 of the parts are defective. Two parts are selected at random without replacement.
Find the probability that both parts are defective.

Aprisoner is trapped in a cell containing three doors. the first door leads to a tunnel that returns him to his cell after two days of travel. the second leads to a tunnel that returns him to his cell after three days of travel. the third door leads immediately to freedom. (a) assuming that the prisoner will always select doors 1, 2 and 3 with probabili- ties 0.5,0.3,0.2 (respectively), what is the expected number of days until he reaches freedom? (b) assuming that the prisoner is always equally likely to choose among those doors that he has not used, what is the expected number of days until he reaches freedom? (in this version, if the prisoner initially tries door 1, for example, then when he returns to the cell, he will now select only from doors 2 and 3.) (c) for parts (a) and (b), find the variance of the number of days until the prisoner reaches freedom. hint for part (b): define ni to be the number of additional days the prisoner spends after initially choosing door i and returning to his cell.

The table showed price paid per concert ticket on a popular online auction site. what was the average price paid per ticket

The ideal weight of a nickel is 0.176 ounce. to check that there are 40 nickels in a roll, a bank weighs the roll and allows for an error of 0.015 ounce in total weight