Leaves at 7:25 p. m. the train from the station 10 km. When does the teacher have to leave the class when he is at 4 km per hour?
And do you want to be at the station a quarter of an hour before the train leaves?

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.