# Standard Index Form

• Oct 31st 2010, 02:41 AM
Roxas
Standard Index Form
1)

Astronomers measure distances in the solar system in astronomical units. (AU)
One AU is 150,000,000km.
The distance from the Sun to Pluto is 395 AU.

How many kilometres is the Sun from Pluto?
Give your answer in standard form to a sensible degree of accuracy.

2)

Write the number 4.5 x 10^-3 as an ordinary number.

3)

Find the value of (2.7 x 10^3) divided by (3.375 x 10^5)
Give answer in standard form.
• Oct 31st 2010, 02:48 AM
Unknown008
Roxas? Okay, well... here we go.

1) What is the distance from the Sun to Pluto? It's 395 AU.

Now, 1 AU = 150,000,000 km
395 AU = 395 x 150,000,000 km = ?

Can you find this first in ordinary number?

2) What does "x 10^-3" mean? Do you know what does "x 10" mean?

3) Do it as follows:

$\dfrac{2.7 \times 10^3}{3.375 \times 10^5}$

Divide 2.7 by 3.375

Then, subtract the power of the 10 in the denominator from the power of 10 in the numerator.

Post what you've got so far.
• Oct 31st 2010, 03:00 AM
Roxas
So for the first one:

395 x 150,000,000 = 59250000000

Which is: 5.925 x 10^10?

2) that's 4.5 times 10 to the power of minus 3.

3) Is the answer 8x10^-3?
• Oct 31st 2010, 03:04 AM
Unknown008
1) Right.

2) Yes, I know. I was asking you what does 10^-3 mean to you. What does the negative power mean? How can you treat it? Does this mean times 1000? Divide by 1000 perhaps?

When you know that, treat it like a normal expression to work out.

3) Right.