Answer:
1.45 milliliters
Explanation:
The given question states that a vial contains radioactive iodine-131 with has an activity of 2.0 mCi/mL. Therefore, if a thyroid test requires 2.9 mCi in an "atomic cocktail", the number of milliliters used to prepare the iodine-131 solution is estimated below:
Using simple mathematics
For an activity of 2.0 mCi/mL, it means that I ml can be used to prepare 2.0 mCi of iodine-131, thus, for 2.9mCi, the number of milliliters required will be:
2.9 mCi/(2.0mCi/mL) = 1.45 mL.
Therefore, 1.45 milliliters are required to prepare 2.9 mCi of iodine-131 solution.