Question
Average of 8 numbers is 70. If average of first four and
last two numbers is 80 and 45, respectively then find the fifth number given that ratio of fifth and sixth number is 4:1, respectively.Solution
Let fifth and sixth numbers be β4xβ and βxβ, respectively. So, 4x + x = 70 Γ 8 β 80 Γ 4 β 45 Γ 2 = 150 Or, 5x = 150 Or, x = 30 So, fifth number = 30 Γ 4 = 120
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