Question
There are three numbers 'a', 'b' and 'c' (a < b < c)
such that 'b' is equal to the average of 'a' and 'c'. 70% of 'c' is equal to 'a' and the difference between 'b' and 'c' is 21. Find the sum of all three numbers.Solution
ATQ, 'b' = (1/2) × (a + c) Or, 2b = a + c And, 0.7c = 'a' Or, c = 10:7 Let 'c' = '10d' and 'a' = '7d' So, 2b = 7d + 10d Or, 'b' = (17d/2) Now, c - b = 21 Or, 10d - (17d/2) = 21 Or, (3d/2) = 21 Or, 'd' = 14 Required sum = 7d + {(17/2) × 14} + (10 × 14) = 98 + 119 + 140 = 357
169, 224, 293, 385, 497, 629
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8, 12, 23, 40, 66, 103
8137, 5405, 3669, 2701, 2201, 1997
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78, 66, 51, 39, 20, 12
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In each of the following number series, one term is wrong. Find the wrong term.
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