Question

The average age of 3 students A.B and C is 48 marks. Another student D joins the group and the new average becomes 44 marks. If Another student E. who has 3 marks more than D. joins the group. the average of the 4 students B. C. D and E becomes 43 marks. Find how many matksA got in the exam.

Answer 1

I)
Average marks of A B and C(mean) = 48marks
n= 3
Sigma I= n* mean
= 3*48
= 144marks

II)
Average marks of A B C and D(mean) = 44 marks
n=4
Sigma II= n* mean
= 4*44
= 176marks

→Marks of D= Sigma II - Sigma I
= 176-144
= 32 marks

→According to question,
Marks of E= Marks of D + 3
= 32+3
= 35 marks

→Average marks of B C D and E(mean)= 43 marks
n= 4
Sigma'= n* mean
= 4*43
= 172marks

→ Marks of B and C= Sigma' - [Marks of D +Marks of E]
= 172 - (32+35)
= 172 - 67
= 105 marks

→Marks of A= Sigma I - Marks of B and C
= 144 - 105
= 39 marks