A dollar bill is 15.5 cm long. If 7 trillion dollar bills were laid end to end around the earth's equator, how many times would they encircle the planet? Radius of planet = 6,378 km.
I keep trying it but I always end up at the number of bills, and the way I'm working it would just give me that answer and then back to the circumference. Can someone tell me how to set this up?
2007-09-04 04:56:20 · 11 answers · asked by Daw 1 in Science & Mathematics ➔ Mathematics
You set it up by considering the laid out bills to be similar to a long string and then dividing their length by the circumference of the earth. (The length of the laid out bills can be obtained from their individual length times the number of them and the circumferenceof the earth can be obtained from the radius of the earth.)
This tells you how many times the "string" will wrap around the earth.
(The answer is 27,074+ times. Rounded to the proper three significant digits, you get 27,100 times.)
2007-09-04 05:03:27 · answer #1 · answered by bimeateater 7 · 0⤊ 0⤋
"How many times they encircle" is really asking "how many circumferences does it add up to." If you can't picture it, get some string and a ball and make a quick model. Or just think about it... it will help though!
Now for the numbers:
Circumference equals 2*pi*r. Here that's 2 * 3.14 * 6378 = 40074 km.
Now you need to figure out how long all the dollar bills are. 7 trillion is 7 * 10^12. That times 15.5 cm = 1.085 * 10 ^14 cm. Remember, you need to convert that into km. The difference is 5 factors of 10 (centimeter is 1/100; kilometer is 1000).
So the length of the bills, in km, is 1.085 * 10^14 / 10^5 = 1.085 * 10^9. You can check yourself on those tricky conversions by thinking about whether the number should go up or down. Because kilometers are bigger than centimeters, you need less of them to cover the same distance. 10^9 is less than 10^15, so you're good.
Now the easy part:
Length of dollar bills (in km) = 1.085 * 10^9
Circumference of earth (in km) = 40074
Divide them, and you get: 2.7 * 10^4, or 27074 circles around the earth.
2007-09-04 05:16:10 · answer #2 · answered by tamar718 1 · 0⤊ 0⤋
circumference of earth at equator = 2.pi.6378 = 40074.15589 km
(taking pi as 3.141592654)
A trillion is a million times a million. So, the length of the dollar bills laid end to end will be
15.5 x 7 x 10^12 cm
Dividing that by 10^5 will give us kilometers
15.5 x 7 x 10^7 kms
Divide that by the circumference of the earth that we got above.
(15.5 x 7 x 10^7) / 40074.15589 = 27074.80609
or let us say 27075 times approximately.
2007-09-04 05:14:09 · answer #3 · answered by Swamy 7 · 0⤊ 0⤋
Its easy:
Firts convert 15.5 cm to Km = 15.5 * 1m/100 cm * 1 Km / 1000m = 1.55 E -4 Km the lenght of each bill
then if youre in USA 7 trillion = 7E 12 dollar bills
Now : lets calculate how much lenght I can obtain with the bills:
1.55 E-4 Km * 7E 12 dollar bills= 1.085 E 9 Km
Finally, you must divide this answer per the circunference of the planet;
1.085 E 9/Km / 2 pi 6378 Km = 27074.8 times around the world
2007-09-04 05:13:58 · answer #4 · answered by skywalkeresearcher 3 · 0⤊ 0⤋
First find the circumference of the Earth. You will need this to solve the problem.
2 * pi* r = (2)(6378)( r) ~ 40,074 km
15. 5 cm = .000155 km
7 trillion dollar bills laid end to end around the equator would be
7,000,000,000,000 * .000155 = 1,085,000,000 km
Since the earth's circumference is 40,074 km, you want to know how many times that will go into 1,085,000,000 km.
1,085,000,000/ 40074 = 27074.911
7 trillion dollar bills laid end to end would circle the planet 27074 (almost 27075) times.
2007-09-04 05:12:07 · answer #5 · answered by Baysoc23 5 · 0⤊ 0⤋
Multiply the length of the dollar bill times with the number of bills you have. Now keep in mind that this number is in cm and it is a big number. First convert cm to meters and then...
You'd have to convert that huge number into kilometers. After that it should be very easy.
You just devide with the circumferance C = pi *d of the planet and it will give you the number of times that these bills would encircle the planet.
I could help you by doing the problem but you seem geniously interested in solving it on your own. Kudos on that.
2007-09-04 05:05:52 · answer #6 · answered by petep73 3 · 0⤊ 0⤋
first find the circumference of the earth
= 2 pi radius = 2 pi 6378 km
= 40074.16 km
= 40074 x 10^3 m
= 40074 x 10^5 cm
1 dollor bill = 15.5cm long
$7 trillion = $7 x 10^9 take $7 x 10^9 x 15.5 cm
= 108.5 x 10^9 cm = 1.085 x 10^9 m
so # of circumference = 108.5 x 10^7 / 4.0074 x 10^7
= 27.075 times round the earth
2007-09-04 05:16:53 · answer #7 · answered by vlee1225 6 · 0⤊ 1⤋
circumference of the Earth is 2 * 6378km * pi = 40074.1558892 km = 40074155.8892 m
the length of 7 trillion bills is 7 000 000 000 000 * 15.5 cm = 1.085 * 10^12 m
divide the length of the bills by the circumference of the Earth
(1.085 * 10^12) / (40074155.8892) = 27074.8
the earth will be encircled 27074.8 times.
2007-09-04 05:13:53 · answer #8 · answered by Merlyn 7 · 0⤊ 0⤋
Assuming a trillion to be 1 million millions (USA English only) than you have (the circumference of earth is almost exactly 40000 km):
15.5 * 7*10^12 / (40000 *1000)= 2712500
2007-09-04 05:05:49 · answer #9 · answered by paulatz2 2 · 0⤊ 2⤋
Radius of planet = 6,378 km
Circumference = 2pi*r=2pi*6,378 km = 40053.84 km
15.5 cm*7 trillion/(100cm/m*1000m/km) = 1,085,000,000km
1085000000/40053.84= 27088.54
2007-09-04 05:05:23 · answer #10 · answered by fcas80 7 · 0⤊ 0⤋