Answer:
The mean of X is 122.5 and the standard deviation is 7.9.
Step-by-step explanation:
For each adult, there are only two possible outcomes. Either they believe that the overall state of moral values is poor, or they do not believe this. The probability of an adult believing this is independent of other adults. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
Probability of exactly x sucesses on n repeated trials, with p probability.
The expected value of the binomial distribution is:

The standard deviation of the binomial distribution is:

In this problem, we have that:

So


The mean of X is 122.5 and the standard deviation is 7.9.
First, you have to set up two equations.
X + y = 45
18x + 24y = 1,050
To do this, you have to solve for an exponent by cancelling out the other one. To solve for y, you multiply everything in the first equation by -18.
-18x -18y = -810
This cancels out the x and leaves you with 6y = 240. Divide both sides by 6 and you have the number of Yankee hats that were bought.
Then, you have to substitute 40 for y in the first equation and solve for x.
Answer: 37
Step-by-step explanation: