Question
There are 15 numbers such that average of first 12
numbers is 30 while the average of last five numbers is 50. Find the 12th number, if the ratio between 11th and 12th number is 6:5, respectively.Solution
Sum of first 12 numbers = (12 x 30) = 360 Sum of last 5 numbers = (50 x 5) = 250 Sum of 11th and 12th number = (360 - 250) = 110 So, 12th number = 110 x (5/11) = 50
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