Q. There are five boxes, each of a different weight & none weighing more than 100. Arun weighs two boxes at a time and obtains the following readings in grams : 110, 111, 112, 114, 115, 116, 117, 119, 120, 121, what is the weight of the heaviest box?

1. 60
2. 61
3. 64
4. Cannot be determined