A series contains 18 numbers and has a sum of 4,185. The last number of the series is 275. What is the first number?

For an arithmetic series, the sum is the number of terms times the average of the first and last terms: 4,185 = 18(a + 275)/2. Dividing by 9 gives a + 275 = 465, so the first number is 190.0, choice B.

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