Use a proportion.
Let A = water used in household A.
Let B = water used in household B.
A to B = 13 to 5
A = 260 gal
260 to B = 13 to 5
260/B = 13/5
13B = 5 * 260
B = 100
A + B = 260 + 100 = 360
The total is 360 gallons.
Answer:
(3.442 ; 6.558)
Step-by-step explanation:
Given :
Mean score after patient is given the magnet treatment :
Mean score, xbar = 5
Standard deviation, s = 2.4
Sample size, n = 20
The confidence interval :
Mean ± margin of error
Margin of Error = Tcritical * standard error
The critical value at 95%, df = 20 - 1 = 19
Tcritical = 2.093 (T-student distribution)
The standard error = s/√n = 2.4 / √20 = 0.5367
The margin of error = 2.903 * 0.5367 = 1.558
The confidence interval :
Xbar ± Margin of error
5 ± 1.558
(3.442 ; 6.558)
All you have to do to calculate the mean average is add the values of the numbers together and then divide that sum by the number of numbers :D.
So in this case:
766 + 878 = 1644
1644 / 2 = 822
The average of these two numbers is 822.