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The average of 17 results is 60. If the average of first 9 results is 57 and that of the last 9 results is 65, then what will be the value of 9th result?1). 392). 783). 1174). 156 |
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Answer» Average of all 17 results is = 60 Sum of all 17 results = 60 × 17 = 1020 Average of first 9 results = 57 Sum of first 9 results = 57 × 9 = 513 Average of LAST 9 results = 65 Sum of last 9 results = 65 × 9 = 585 Both SUMS I.e. of first 9 and last 9 digits include the 9 result So if we add both sums it will have the 9th result one extra time and we can subtract the actual sum from this ADDITION to GET the 9th result So sum of first and last 9 results = 513 + 585 = 1098 ∴ The 9th result will be = 1098 - 1020 = 78 |
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