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Unknown008 · Sep 2, 2010, 01:37 AM

You are used to the British system?

Ok, let's change this.

Um... My computer is besides me. I am 2400 miles away from you. How far is my computer from you?

ashlayy101 · Sep 2, 2010, 01:40 AM

2.2?

Unknown008 · Sep 2, 2010, 01:43 AM

Don't you think that it's 2400 miles away from you? Do you get it or, do you still have something somewhere you're not sure about?

ashlayy101 · Sep 2, 2010, 01:48 AM

I just completely don't get it. All the book really says is to change km to m? I don't know how to do that and when I answer the question I have to put in Type in scientific notation, 4 x 1013 would be typed in as 4e13 like this? Well I don't how to get the answer from 8.86 X 10e10

Unknown008 · Sep 2, 2010, 01:51 AM

In fact the answer is $8.86 \times 10^{10}\ km$ .

Let's take a smaller distance. You are in your house. The market is 10 yards away from your house. How far are you from the market, in yards?

ashlayy101 · Sep 2, 2010, 01:56 AM

I know every 1 yard is 3 feet so 10 x 3=30ft
so if you want yards wouldn't it be 10?

Unknown008 · Sep 2, 2010, 01:59 AM

Right! But you didn't have to calculate anything here! The answer was already given to you! Do you see now? :)

ashlayy101 · Sep 2, 2010, 02:03 AM

Yes! So for "A" I did multiply 10 X 8.86 = 88.6 now the total answer is 88.6e12... I just honestly don't know how 12 is even in there or how I got it because I just figured 10e10 so I just started putting numbers down till I got the right answer

Unknown008 · Sep 2, 2010, 02:08 AM

Ok, now to the question.

The distance of the probe is 8.86e10 km from the Earth.

Recall that 1 km = 1000 m.

So, in metres, 8.86e10 km = 8.86e10 x 1000 = 8.86e13 m

This is using scientific notation. It's just like:

$8.86 \times 10^{10}\ \times\ 1000 = 8.86 \times 10^{10} \times 10^3 = 8.86 \times 10^{(10+3)} = 8.86 \times 10^{13}$

Now, we come to the time it takes. Can you find it?

$Speed = \frac{Distance}{Time\ Taken}$

So,

$Time\ Taken = \frac{Distance}{Speed}$

ashlayy101 · Sep 2, 2010, 02:16 AM

So would I set up this problem like this time taken=88.6/3.00=29.5
or time take=88.6/1000

Unknown008 · Sep 2, 2010, 02:22 AM

$Time \ Taken = \frac{Distance}{Speed}$

So, we have:

$Time\ Taken = \frac{8.86\times10^{13}}{3\times 10^8}$

You need to put everything in the number.

Maybe the scientific notation is not clear...

$8.86\times 10^{13} = 88600000000000$

$3 \times 10^8 = 300000000$

Getting back,

$8.86\times 10^{10} km = 88600000000 km$

$88600000000 km = 88600000000 \times 1000 m = 88600000000000 m$

ashlayy101 · Sep 2, 2010, 02:31 AM

Im sorry, I still don't get it. I am sorry if I am frustrating you =/

Unknown008 · Sep 2, 2010, 02:34 AM

It's okay. It's just that I am thinking about how to go and make you understand... maybe this way...

Find:
I) 2 x 10 = ?
ii) 58 x 100 = ?
iii) 6.5 x 10000 = ?
iv) 3 x 10e2 = ?

ashlayy101 · Sep 2, 2010, 02:42 AM

20
5800
65000
300

Unknown008 · Sep 2, 2010, 02:43 AM

For the last one, no.

3 x 10e2 = 3 x 10 x 100 = 3000

okay?

If this was: 3 x 1e2, then this becomes 3 x 1 x 100 = 300

ashlayy101 · Sep 2, 2010, 02:47 AM

OK

Unknown008 · Sep 2, 2010, 02:48 AM

Ok, now this one:

3e5 x 6e2 = ?

ashlayy101 · Sep 2, 2010, 02:59 AM

300,000 x 600= 180,000,000

Unknown008 · Sep 2, 2010, 03:04 AM

Correct. Now, you'll see something too.

180,000,000 in scientific notation is 1.8 x 10^8 , or 1.8e8

What happened?

3e5 x 6e2 = (3 x 6) x e(5 + 2) = 18e7

Now, this is 18 x 10^7 right?

or

(1.8 x 10) x 10^7

This becomes 1.8 x 10^8

Try these now, using this new way of multiplying numbers, giving your answer in scientific notation.

1e16 x 8e18 = ?

5e12 x 3e8 = ?

9e7 x 7e6 = ?

ashlayy101 · Sep 2, 2010, 03:13 AM

I am starting to understand so would I use these tools to figure out "B"