The average weight of 9 boxes is 61kg. If three boxes having an average weight of 70 kg are removed, then what will be the new average weight of the remaining boxes?
Answer & explanation
Correct answer: option 3
The average weight of 9 boxes = $\frac{Sum\;of\;weights}{9}$
⇒ $\frac{Sum\;of\;weights}{9}$ = 61
⇒ Sum of all weights = 61 x 9 = 549
If three boxes of average weight 70 kg are removed, total of (70 x 3) 210 kg is removed.
Weight of 6 boxes = weight of 9 boxes - 210
= 549 - 210 = 339
⇒ New average = $\frac{Sum\;of\;6\;boxes}{6}$
= $\frac{339}{6}$ = 56.5 kg