Answer:

And replacing we got:

And we can calculate this probabilit using the normal standard distribution or excel and we got:

Step-by-step explanation:
If we define the random variable of interest "the amount spent by a family of four of food per month" and we know the following parameter:

And we want to find the following probability:

And we can use the z score formula given by:

And replacing we got:

And we can calculate this probabilit using the normal standard distribution or excel and we got:

Answer:
4000 gallons.
Step-by-step explanation:
One day's discharge at the mouth of the river is 2 trillion gallons and it can supply all of country A's households for five months.
Now, if there are 100 million households in country A.
Then, the amount of water an average household uses each month will be given by
gallons. (Answer)
Subtract 2
y-2=1/2 x
Multiply by 2 to cancel out the denominator and to get 1 in front of x
2(y-2)=x
You can stop there or you can multiply out.
2y-4=x
X/5 = 8/9
this is a proportion, so we cross multiply
(9)(x) = (5)(8)
9x = 40
x = 40/9 or 4 4/9
D to B =180
B to D=180
D to C =19