Multiple choice

Directions: Choose the correct alternative from the given ones that will complete the series. 78, 155, 309, ?, 1233

  1. 625

  2. 1230

  3. 1000

  4. 617
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D Correct answer
Explanation

The pattern is: 78 * 2 - 1 = 155; 155 * 2 - 1 = 309; 309 * 2 - 1 = 617; 617 * 2 - 1 = 1233.

AI explanation

The series follows the logic of multiplying by 2 and subtracting 1. Applying this, 78 multiplied by 2 gives 156, and subtracting 1 yields 155. Similarly, 155 multiplied by 2 is 310, and subtracting 1 gives 309. For the missing term, 309 multiplied by 2 equals 618, and subtracting 1 results in 617. The missing number is 617.

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