Can you circle exactly four of these numbers such that the total is twelve?

Five potential donors are sitting on a bench from left to right outside the surgery room and are waiting for the doctor. Their ages are 6, 10, 31, 47 and 61. Their heights are 41, 49, 61, 66 and 75 inches. Their weights are 41, 76, 97, 126 and 166 pounds.
Determine the position, blood group, age, height and weight of each of them with the help of the following ten hints.
A bathtub has two taps and a plug hole. The cold tap on its own fills the bathtub in 18 minutes. The hot one on its own fills the bathtub in 15 minutes. The plug hole can drain the bathtub in 10 minutes with the taps off.
How long will the bathtub take to fill if both taps are turned on and the plug left out?
Riddle AnswerSuppose we lay down two cups in front of you. One of the cups is filled with tea and the other one with coffee. Now we ask you to take a spoonful of tea and mix it with the coffee. At this moment, the coffee cup has a mixture of tea and coffee. You have to take that mixture (spoonful) and add it back to the tea.
Can you now tell if the cup of coffee has more tea or the cup of tea has more coffee?
Riddle AnswerSix men, namely Martin Freeman, Jonah Jameson, Terry Singer, Mike Cooper, Jim Condon and Sylvian Bogard were in an elevator together.
Unexpectedly, the lights went out. When the lights came back, Martin Freeman’s wallet was missing which contained a confidential item.
Detectives were called at the scene. They interrogated the suspects, the witnesses, and people who were familiar with the suspects. They collected physical evidence (hair samples, fiber samples, etc.) from the crime scene as well. Overall, they were able to collect fifteen clues, but they could still not find the culprit.
Following are the clues.
Can you find the culprit?
Riddle Answer