A certain radioactive substance has a half-life of 28.6 hours. If injected into

Question

A certain radioactive substance has a half-life of 28.6 hours. If injected into the bloodstream, the substance accumulates in the thyroid gland. ?? Part 1 a. After 34 hours, a medical technician scans a patient's thyroid gland to determine whether thyroid function is normal. If the thyroid has absorbed all the substance, what percentage of the original amount should be detected? If the thyroid has absorbed all the substance, approximately 11 should be detected. Round your answer to one decimal place. Correct answer: 43.9 % of the original amount Part 2 out of 2 b. A patient returns to the medical clinic 38 hours after having received an injection of the radioactive substance. The medical technician scans the patient's thyroid gland and detects the presence of 36.4% of the original substance. How much of the original substance remains in the rest of the patient's body? % of the original substance. Round your answer to one The rest of the body will contain decimal place.

Explanation / Answer

Part A.

Given that half-life of the substance is 28.6 hours.

After 34 hours the substance was checked.

The number of half-lives that have elapsed = (34/ 28.6) = 1.18

Fraction remaining = 100/2n where n is the number of half-lives elapsed. So, 100 * ½ 1.18 = 44% of the original sample will be remaining.

Part B.

After 38 hours, the amount of substance remaining will be (100/238/28.6) = 39.8%.

Now, it is given that 36.4% is found in the thyroid gland, so, amount of substance in rest of the patient’s body is (39.8 - 36.4) = 3.4%

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