Solution
Understanding the Set:
- This is a question-based set. In this set, you are told that there are 16 patients and 8 vials — labeled A, B, C, D, E, F, G, and H.
(Vials are simply the containers in which blood samples are stored.)
- It is also given that only one person has the disease.
- If a patient has the disease, then every vial containing his/her blood sample will test positive.
a) If a vial tests positive, at least one of the patients whose blood samples were mixed in that vial has the disease.
b) If a vial tests negative, then none of the patients whose samples were mixed in that vial has the disease.
This set might initially seem a bit confusing, but it was actually one of the simplest sets asked.
The key was to understand the passage correctly — once that was done, the questions were softballs.
| Patient | Vials | Patient | Vials |
|---|---|---|---|
| 1 | B, D, F, H | 9 | A, D, F, H |
| 2 | B, D, F, G | 10 | A, D, F, G |
| 3 | B, D, E, H | 11 | A, D, E, H |
| 4 | B, D, E, G | 12 | A, D, E, G |
| 5 | B, C, F, H | 13 | A, C, F, H |
| 6 | B, C, F, G | 14 | A, C, F, G |
| 7 | B, C, E, H | 15 | A, C, E, H |
| 8 | B, C, E, G | 16 | A, C, E, G |
Since every patient's blood sample is there in vials
so with a mixing of two non-diseased patient's blood samples there will be vials with positive test result.
Let one of the patients,
patient 1 or patient 16 has the disease and his blood is mixed with other them all 8 vials will tests positive. ⇒ 8 has to be one of the answers.
If patient 2 and patients 16’s blood is mixed of one of them has the disease then 7 of the 8 vials will test positive.
=> So 7 has to be there in the option.
If 1 has the disease and 1, 7 are mixed then 6 out the 8 vials tests positive.
IF 1 has the disease and 1,9 are mixed then 5 of the 8 vials tests positive,
Now, let us assume that patient 1 has the disease if his blood is not mixed, then 4 vials will definitely show positive.
So the correct answer is 3rd option
More from this set:
Question 1