# A fictitious element that has two isotopes has an average atomic mass of 117.3. If 65.43% of the atoms of the element have an atomic mass of 119.8, what is the atomic mass of the other isotope?

##### 1 Answer

Sep 6, 2017

#### Answer:

Approx...

#### Explanation:

The weighted average of the isotopes is equal to

And thus.........with units of

Where

And so we solve for