Question
Average of 8 numbers is 80. If average of first four and
last two numbers is 90 and 60, respectively then find the fifth number given that ratio of fifth and sixth number is 5:3, respectively.Solution
Let fifth and sixth numbers be ‘5x’ and ‘3x’, respectively. So, 5x + 3x = 80 × 8 – 90 × 5 – 60 × 3 = 160 Or, 8x = 160 Or, x = 20 So, fifth number = 20 × 5 = 100
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