Question

A culture of 1.08×1015 bacteria is in petri dish A. A culture of 2.7×1011 bacteria is in petri dish B.

How many times greater is the number of bacteria in petri dish A than petri dish B?

Please explain how do this without having to type a million zeroes!?

Answer 1

4 * 10^3 or 4000

Explanation:

A = 1.08 * 10 ^ 15

B = 2.7 * 10 ^ 11

we want to divide them

1.08 * 10 ^ 15

-------------------------

2.7 * 10 ^ 11

when we divide scientific notation, we divide the numbers, and subtract the exponents

(1.08/2.7) * 10 ^ (15-11)

.4 * 10 ^4

but this is not correct scientific notation because we need 1 number before the decimal

since we have to move the decimal 1 place to the right, we decrease the exponent 1 place

4 * 10 ^ (4-1)

4 * 10^3

this is 4 with 3 zero's

4000