The average of 11 numbers is 71 and the average of the first five numbers is 67. If the average of the last four numbers is 91.5 and the ratio of the ...
Question
The average of 11 numbers is 71 and the average of the first five numbers is 67. If the average of the last four numbers is 91.5 and the ratio of the sixth and seventh numbers is 9 : 7, then find the sixth number.