The graph shows the relationship between the total cost and the number of gift cards that Raj bought for raffle prizes. A graph titled Cost of Gift Cards. The x-axis shows the number of gift cards, numbered 1 to 9, and the y-axis shows the total cost in dollars, numbered 10 to 90. Blue diamonds appear at points (1, 20), (2, 40), (3, 60), (4, 80).
What would be the cost for 5 of the gift cards?

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.