This is because you have to set it equal to the total cost witch is C. Now you put have to put 25n as the number of toy's manufactured . Then set 9800 up as what is added to the money added to the money per toy made. This is how i got my answer.
The standard deviation of the sample proportion is: The z-score for 0.7 is: Reference to a standard normal distribution table shows that the probability that at least 70% of the sample prefers coke to pepsi is 0.8944 or 89.44%.