It took Sergio 1.5 hours to read 3 chapters of a book. If he continues reading at a constant rate and the chapters are similar in length, how many hours will it take Sergio to complete the entire book if it is 18 chapters long?

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.