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What is the average of first 30 multiples of 9?1). 1422). 138.53). 139.54). 143.5 |
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Answer» Sum of the nth term = n/2 × (2a + (n – 1) × d) n = number of terms a = first term d = Common difference Sum of the 30th terms = 30/2 × (2 × 9 + (30 – 1) × 9)(n = 30, a = 9, d = 9) = 15 × (18 + 29 × 9) = 4185 Sum of the first 30 multiples of 9 = 4185 ∴ Average of the first 30 multiples of 9 = 4185/30 = 139.5 |
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