Ken and Mark have some ducks and pigs. When asked how many ducks and pigs they had altogether, Mark said: "There is a total of 17 heads and 42 feet. I have three times as many ducks as pigs." "Yes," replied Ken, "and we both have the same number of pigs." How many ducks does Ken have?

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.