Question
Average of 8 numbers is 30. If average of first four and
last two numbers is 20 and 50, respectively then find the fifth number given that ratio of fifth and sixth number is 7:5, respectively.Solution
Let fifth and sixth numbers be ‘7x’ and ‘5x’, respectively. So, 7x + 5x = 30 × 8 – 20 × 7 – 50 × 5 = 60 Or, 12x = 60 Or, x = 5 So, fifth number = 5 × 7 = 35
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