Question

The weight of an adult blue whale is 9 x 10^4 kilograms; the weight of an elephant is 3 * 10^3 kilograms. How many times heavier is the whale than the elephant?a.30b. 30000c.300d.3000

Answer 1

The weight of the wale is:

$9\times10^4$

kilograms.

And the weight of the elephant is:

$3\times10^3$

kilograms.

There are two ways to solve this problem, one is to think about which number we have to multiply 3x10^3 to become 9x10^4. And the other way, which is more direct, is to divide the bigger number (9x10^4) by the smaller number (3x10^3):

$\frac{9\times10^4}{3\times10^3}$

To make this division, first, we divide 9 by 3 and the result is 3:

$3\times\frac{10^4}{10^3}$

Now we divide 10^4 by 10^3, to divide this type of expressions what we do is subtract the exponents:

$\frac{10^4}{10^3}=10^{4-3}=10^1=10$

Now we substitute this and we get:

$3\times10$

which is equal to:

$3\times10=30$

Since the division of the number is 30, the whale is 30 times bigger than the elephant.

Answer: A. 30