The average weight of 47 students in a class is 52 kg. 5 of them whose average weight is 48 kg leave the class and other 5 students whose average weight is 54 kg join the class. What is the new average weight (in kg) of the class ?
Choose the correct choice:  A) 51 1⁄47  B) 52 30/47  C) 52 1⁄30  D) 43.42  E) None of these
Total weight of 47students   = 47 × 52 = 2444 kg   Total weight of 5 students who leave   = 5 × 48 = 240 kg   Total weight of 5 students who join   = 5 × 54 = 270 kg   Therefore, new total weight of 47 students   = 2444 – 240 + 270 = 2474   ⇒ New average weight = 2474⁄47 = 52 30/47 kg   Answer 52 30/47
<result>B</result>
The average weight of 47 students in a class is 52 kg. 5 of them whose average weight is 48 kg leave the class and other 5 students whose average weight is 54 kg join the class. What is the new average weight (in kg) of the class ?