A student number system for a county requires that the student number be 5 characters. The first character is a consonant, the second through the fourth characters can be any digit but no digit can repeat and the last character must be a
letter. How many unique student numbers are possible?

546,000 student numbers
393,120 student numbers
302,400 student numbers
468,000 student numbers

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.

For the word below, click on the drop-down arrows to select the root and its meaning. version

Here is another math questions. i will keep asking different questions. 4^2x=6