The average weight of a group of boys is 30 kg. After a boy of weight 33 kg joins the group, the average weight of the group goes up by 1 kg. Find the number of boys in the group originally ? Choose the correct option
A) 4  B) 5  C) 2  D) 7  E) 8
Let the number off boys in the group originally be x.   Total weight of the boys = 30x   After the boy weighing 33 kg joins the group, total weight of boys = 30x + 33   So 30x + 33 = 31(x + 1) = &gt; x = 2.   Answer: 2
<result>C</result>
The average weight of a group of boys is 30 kg. After a boy of weight 33 kg joins the group, the average weight of the group goes up by 1 kg. Find the number of boys in the group originally ?