The average of 13 numbers is 10.9. If the average of the first seven numbers is 10.5 and that of the last seven numbers is 11.4, then the middle number is	Options
A) 15.6  B) 11.6  C) 12.6  D) 13.3  E) 14.4
Explanation:   Middle numbers = [(10.5 x 7 + 11.4 x 7) - 10.9 x 13] = (131.4 - 119-9) = 11.6 Answer: 11.6
<result>B</result>
The average of 13 numbers is 10.9. If the average of the first seven numbers is 10.5 and that of the last seven numbers is 11.4, then the middle number is