Question

Seventy percent of the Earth's surface is covered with water. find the approximate surface area of the Earth that is water? find the volume

Answer 1

Here again, just calculate the surface of a sphere with radius 3963 miles. Then get 70% of it (which is nothing but 0.7*surface area)

Answer 2

for the surface area i get 1.97359488E8

Answer 3

That is correct. Now multiply that by .7. Also, do you know what the E8 at the end means?

Answer 4

no

Answer 5

E8 means times 10^8. So, 1000 is 1.00E3, which means 1 * 10^3. So in your case, 1.9735E8 means 1.9735 * 10^8. Avoid using calculators if you can.

Answer 6

1.9735 * 10^8*.7 is the surface area?

Answer 7

that is the surface area of water on earth. * means multiplication here.

Answer 8

138 145 000

Answer 9

138081604.2 is the correct answer, because you approximated yours (you used the approximate number I gave). But did you understand the whole process?

Answer 10

yeah.. so than for the volume i got 2.60711891E11

Answer 11

That is correct.

Answer 12

I don't know if it is acceptable to put E11 here, but I'd just move the decimal place to the end. Can you use a scientific calculator with more space?

Answer 13

2.60711891*10^11

Answer 14

mine is broken

Answer 15

260711891. so like this with no decimal?

Answer 16

With no decimal, it will be 2.60711891 * 100000000000 = 260711891000. Remember, the decimal shifts by the number of zeros. So for example, 2.2 * 10^3 shifts the decimals by 3 places. So 2.2 * 10^3 or 2.2 * 1000 becomes 2200 (you have to start adding 0s if you run out of numbers to move the decimal places by). Another example, 4.55676 * 10^3 = 4556.76 and 4.55676 * 10^8 would be 455676000. Can you tell me what 6.887 * 10^5 will be?

Answer 17

688700000

Answer 18

No - you added too many 0s. Here's how it works. 6.887 * 10^5 means that you have to move the decimal 5 places. So, moving it one place makes it 68.87. Moving it two places will make it 688.7 and moving it three places will make it 6687. Now, to move it one more place, you'll have to add a 0 - so moving it four places will be 66870 and moving it five places will be 668700 - which is the correct answer. Try these two problems. 1) What is 7.99889834E6 without decimals? 2) What is 913.223 * 10^4 without decimals?

Answer 19

7998898

Answer 20

9132230

Answer 21

Very good - the first answer, you still have to put in the decimal, so 7.99889834E6 will be 7998898.34 (sorry if I confused you by saying without decimals - I should have said, without the E6). The second answer is correct.