The average weight of a group of boys is 30 kg. After a boy of weight 38 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 one:	A) A)4	B) B)8	C) C)6	D) D)2	E) E)7
Let the number off boys in the group originally be x.   Total weight of the boys = 30x   After the boy weighing 38 kg joins the group, total weight of boys = 30x + 38   So 30x + 38 = 31(x + 1) = &gt; x = 7.   Answer:7
<result>E</result>
The average weight of a group of boys is 30 kg. After a boy of weight 38 kg joins the group, the average weight of the group goes up by 1 kg. Find the number of boys in the group originally ?