The average score in an English exam of a class of 45 students in a coaching centre is 52. A group of 6 boys

The average score in an English exam of a class of 45 students in a coaching centre is 52. A group of 6 boys having an average score of 40 leave the class and another group of eight boys having an average score of 43 join the class. What is the new average score of the class?

a)            52

b)            55

c)            60

d)            62

Sol:

Total marks in 1st case 45×52= 2340

6 boy left with avg 40 means 6×40= 240 marks out marks left 2340–240= 2100, boys left= 39

8 boy joined with avg 43 so 8×43= 344 marks in new marks 2100+344= 2444 , boys now 39+8=47

So new avg 2444/47 = 52