High School

Select the correct answer.

A dust particle weighs [tex]$7.42 \times 10^{-10}$[/tex] kilograms. What is the weight of [tex]$5 \times 10^6$[/tex] dust particles represented in scientific notation?

A. [tex]3.71 \times 10^{-4}[/tex] kilograms
B. [tex]3.71 \times 10^{-3}[/tex] kilograms
C. [tex]37.1 \times 10^{-3}[/tex] kilograms
D. [tex]37.1 \times 10^{-4}[/tex] kilograms

Answer :

Sure! Let's solve this problem step by step.

We are given that one dust particle weighs [tex]\(7.42 \times 10^{-10}\)[/tex] kilograms. We need to find the total weight of [tex]\(5 \times 10^6\)[/tex] dust particles.

1. Multiply the weight of one particle by the number of particles:

[tex]\[
\text{Total weight} = \left(7.42 \times 10^{-10} \, \text{kg}\right) \times \left(5 \times 10^6\right)
\][/tex]

2. Multiply these numbers together:

- First, multiply the coefficients: [tex]\(7.42 \times 5 = 37.1\)[/tex]
- Then, add the exponents: [tex]\(-10 + 6 = -4\)[/tex]

So, the scientific notation of the total weight is:

[tex]\[
37.1 \times 10^{-4} \, \text{kg}
\][/tex]

3. Look at the choices given and find the matching one:

A. [tex]\(3.71 \times 10^{-4}\)[/tex] kilograms
B. [tex]\(3.71 \times 10^{-3}\)[/tex] kilograms
C. [tex]\(37.1 \times 10^{-3}\)[/tex] kilograms
D. [tex]\(37.1 \times 10^{-4}\)[/tex] kilograms

The correct answer is:

D. [tex]\(37.1 \times 10^{-4}\)[/tex] kilograms

Thus, the weight of [tex]\(5 \times 10^6\)[/tex] dust particles is [tex]\(37.1 \times 10^{-4}\)[/tex] kilograms.