Question

the average Wight of 9 boys is 42 kg another boy joined the class and the new average was found to be 42.5kg find the Wight of the new boy

Answer 1

47 is the weight of new boy
formula average =sum/no.of boys
n1=9 avg=42 s1=42*9=378
n1=10 because new boy was added
avg2=42.5 s2=10*42.5=425
difference(425,378)=47
got it

Answer 2

Answer:

47 because there new boy joined group