Each question on a multiple-choice exam has four choices. one of the choices is correct, worth four points. another choice is wrong but carries partial credit of one point. the other two choices are wrong and worth negative one point. if a student picks answers at random, what is the expected value of his or her score for a problem?
a 0.75
b 0.25
c 1.25
d 1.50

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?