Question
The average of six numbers is 8. When three new numbers
are included in such a way that the first number is  twice the second and second number is thrice the third, now the average of nine numbers becomes 12. What will be the difference of first and third among the new numbers?ÂSolution
Sum of five numbers = 6 × 8 = 48 Let the third number be x, Second number will be 3x, First number will be 6x According to the question, (48+6x+3x+x)/9=12 ;  (48+10x)/9=12; x=  (108-48)/10 x=6 ∴ the three numbers will be 6, 18 and 36 ∴ Difference of first and third no.= 36 – 6 = 30
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