When multiplying by multiples of 10, move the decimal place one place over to the right. 44,000 becomes 440,000.
The difference in gallons per day used is 3.6.
The formula to calculate a z-score is:

,
where X is the value used to calculate the score, μ is the mean and σ is the standard deviation. We have the z-scores so we must work backward:

For both equations, we will cancel the 1.2 by multiplying both sides:

Now we will cancel 2.2 from both equations by adding it to both sides:
3.6+2.2=X-2.2+2.2 and 0+2.2=X-2.2+2.2
5.8=X and 2.2=X
The difference in gas used per day would be given by
5.8-2.2 = 3.6.
Answer:
Actual mean: 223 pages
Predicted mean / estimate: 225 pages
Explanation below
Step-by-step explanation:
Mean = total amount ÷ # of numbers
155 + 214 + 312 + 198 + 200 + 170 + 250 + 260 + 215 + 256
Add
2,230
# of numbers = 10
2,230 ÷ 10 = 223
The exact mean is 223
If I were to predict the mean, I would say that a good estimation would be around 225, because I see that the highest number in the data set is 312, and the lowest is 155. If 312 is rounded down to 300, and 155 is rounded down to 150, the number exactly in the middle of 300 and 150 is 225.
Actual mean: 223 pages
Predicted mean: 225 pages
Hope this helps :)
Answer:
b) 9
Step-by-step explanation:
9 squared + 40 squared = 41 squared, which follows Pythagorean theorem.