Question

Question #40a6a

Answer 1

256 milligrams

Explanation:

If we convert 64kg to milligrams, there is 64, 000, 000 mg of person (a funny concept!) as there are 1 million milligrams in a kilogram.
So, if there are four parts for each million, and there are 64 million grams, then there will be `64xx4=256` milligrams

Hope this helps; let me know if I can do anything else:)

Answer 2

`256.00` `"mg"`

Explanation:

The average concentration of `"PCB"`s in the body tissue of a human is `4.00` `"ppm"`.

Let's convert the units of the concentration from `"ppm"` to `"mg"` / `"kg"`:

`⇒ 1` `"ppm"` `= 1` `"mg"` / `"kg"`

`⇒ 4.00` `"ppm"` `= 4.00` `"mg"` / `"kg"`

We need to find the mass of `"PCB"`s found in a `64` `"kg"` human.

So let's set up a ratio using this information:

`⇒ frac(4.00 " mg")(1 " kg") = frac(x)(64 " kg")`

Multiply both sides by `64` `"kg"`:

`⇒ frac(4.00 " mg" × 64 " kg")(1 " kg") = frac(x × 64 " kg")(64 " kg")`

`⇒ 256.00` `"mg"` `= x`

`∴ x = 256.00` `"mg"`

Therefore, the mass of `"PCB"`s present in a `64` `"kg"` person's body is `256.00` `"mg"`.