15. a new section of 12-inch diameter pipe is to be disinfected before it is put into service. if the length of the pipeline is 1200 feet, how many gallons of water will be needed to fill it?

7050 gallons

Step-by-step explanation:

The pipe is cylindrical, so the volume is:

V = πr²h

Given:

r = 12/2 = 6 inches = 0.5 feet

h = 1200 feet

Substituting:

V = π (0.5 ft)² (1200 ft)

V = 942.5 ft³

One cubic foot is 7.48 gallons, so:

V = 7050 gallons

11-2x and 2x-11 and 32+10x-(21+12x) and 32-21+10x-12x

Step-by-step explanation:

Let's start by changing the words into math.

MIKAYLA: "Mikayla has $32 in her piggy bank." tells us that she had 32 dollars. " Mikayla earns $10 a week by doing chores for her grandparents" tells us that she gets 10x dollars after x weeks. Adding these together we get 32+10x.

JESSICA: "Her sister, Jessica, has $21" tells us that she had 21 dollars. "while Jessica earns $12 a week by mowing lawns" tells us that she gets 12x dollars after x weeks. Adding these together we get 21+12x.

The question wants us to find how much more money Mikayla has so we subtract equation 1 from 2. Thus, 32+10x-(21+12x). (This gives us the fourth answer to be correct). Simplifying this we get 32-21+10x-12x (this gives us the last answer). Simplifying it even more we get 11-2x (this gives us the first question).

Also the question need how much less money Mikayla has so we can subtract equation 2 from 1 to get 2x-11 (which is the third answer).