Technicians have installed a center pivot, circular irrigator for a farm that covers 20 acres.How long is the irrigation boom (in feet) from the center pivot to its farthest extent?

Image attached

Question

Technicians have installed a center pivot, circular irrigator for a farm that covers 20 acres.How long is the irrigation boom (in feet) from the center pivot to its farthest extent?

Image attached

mertsj · Answer

1 acre = 43,560 ft^2
20 acres=871200 ft^2=area of circle=pir^2
$$\pi r^2=871200$$
$$r^2=\frac{871200}{\pi}$$
$$r=\sqrt{\frac{871200}{\pi}=}277311.6 ft$$

anonymous · Answer

wow merts can you help wit 2-3 more please

anonymous · Answer

that didt work for me (the 277311.6

anonymous · Answer

yea and it didnt either

mertsj · Answer

Oh.  Time out.  I think I forgot to take the square root.  Let me check.

mertsj · Answer

526.6 feet

anonymous · Answer

yeah that works. can youe help me with the second part please

mertsj · Answer

What's the second part?

anonymous · Answer

If the irrigation boom makes 4 full revolutions in a day, how many miles does the end of the boom travel in  days?

mertsj · Answer

$$C=2\pi r=2\pi (526.6)=3308.75 ft = 1 rev$$

mertsj · Answer

$$4(3308.75ft)=13235.0 ft$$

mertsj · Answer

$$13235 ft \times \frac{1 mi}{5280 ft}=2.5 mi$$

mertsj · Answer

"how many miles does the end of the boom travel in  days?  Is there supposed to be a different number of days than 1?

anonymous · Answer

3 days. sorry

mertsj · Answer

So then 7.5 miles.

anonymous · Answer

ok

anonymous · Answer

The compound interest formula is F=(1+i)^n  where F is the total amount due, P  is the initial cost or amount of money, i is the interest rate, and n is the number of periods interest is computed. 

 A student purchases a 1300$ laptop computer for school. The deal does not require payment until  2 years later. If interest is computed monthly, how much does the student have to pay at the end of  2 years? The monthly interest rate is 1.8 percent. 

 $ 

 If the cost of the laptop is the same, how much does the student owe if the interest rate is  216  percent computed annually?

mertsj · Answer

$$F=P(1+\frac{r}{n})^{nt}$$

mertsj · Answer

Are you sure that's not the compound interest formula?

anonymous · Answer

its not what i was given

mertsj · Answer

Yours doesn't have P in it at all.

anonymous · Answer

oh sorry. I have F=P(1+i)^2

mertsj · Answer

$$F=1300(1+.018)^{24}$$
$$F=$1994.76$$

mertsj · Answer

And shouldn't the exponent be n instead of 2?

mertsj · Answer

And for the next part...surely the interest rate is not 216%

anonymous · Answer

it actually is. your right. its 21.6 %

anonymous · Answer

the exponent is n and the interst rate is 21.6

mertsj · Answer

$$F=1300(1+.216)^2$$
$$F=$1922.25$$

anonymous · Answer

this the last one 
A probe sent to the surface of Mars uncovers a pure platinum disc inscribed with the message, "We'll be right back" (in Martian, of course!). The disc is inches thick and meters in diameter. The density of platinum is 21,450 . What is the mass of the platinum disc in pounds ()?

 The Martian acceleration due to gravity is 3.61 while Earth's gravitational constant is 32.2 . What is the Earth weight of the disc in Newtons?

anonymous · Answer

2 inches thick and  0.9 meters in diameters

anonymous · Answer

21450 kg/m^3

anonymous · Answer

3.61m/s^2 and 32.2ft/s^2