Answer:
New mean will be 12
And no change in standard deviation
Step-by-step explanation:
We know the relationship between the two mean and standard deviation


If we add 2 to each value of x that means the mean will become n will become 2n and since we are adding 2 to each value
The new mean will become 12
And there will be no change in the standard deviation because of equal change in the each data.
It really does not matter, I tend to solve for x first simply because it comes before y, but you do whatever is easier for you.
424.8 gallons because you have to multiply the number of miles per gallon by the amount of gallons that the tank can hold. 23.6 times 18= 424.8