Question

A sample of DNA has 10% Guanine. What is the percentage of Thymine in that sample?

Answer 1

`40%`

Explanation:

Guanine (G) in DNA is one-to-one coupled to cytosine (C), so that also makes up for 10%.

Then there's 80% left for the other one-to-one couple: Thymine (T) and adenine (A). So 40% T and 40% A.

Answer 2

`40%`

Explanation:

In `"DNA"`, adenine `("A")` always bonds with thymine `("T")`, while guanine `("G")` always bonds with cytosine `("C")`.

So, the percentages of `"A"` and `"T"` will be equal, while the percentages of `"G"` and `"C"` would also be equal.

In this sample, there exist `10%` of guanine, therefore there's also `10%` of cytosine. Therefore, thymine and adenine would make up a total of `100%-10%-10%=80%` of the `"DNA"`.

As they must exist in equal amounts, the percentage of thymine in this `"DNA"` sample will be `80%-:2=40%`.