A computer system uses passwords that consist of 4 letters followed by an even digit. (a) How many passwords are possible? Write S.
(b) How many passwords consist of 3X’s and Y’s and end in a single digit? Write S.
(c) If any forget password but remember that it has the characteristics described in part (b) what is the chance that one will guess the password correctly on the first attempt?

I’m really confused and need to learn this

Afair die is cast four times. calculate the probability of obtaining exactly two 6's round to the nearest tenth of a percent

Titus works at a hotel. part of his job is to keep the complimentary pitcher of water at least half full and always with ice. when he starts his shift, the water level shows 4 gallons, or 128 cups of water. as the shift progresses, he records the level of the water every 10 minutes. after 2 hours, he uses a regression calculator to compute an equation for the decrease in water. his equation is w –0.414t + 129.549, where t is the number of minutes and w is the level of water. according to the equation, after about how many minutes would the water level be less than or equal to 64 cups?