At the city museum, child admission is $6.60 and adult admission is $9.70. on friday, 136 tickets were sold for a total sales of $1089.80. how many child tickets were sold that day? !

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.