Multiple choice

Find 9th term of the following series 5, 10, 20, 40

  1. 1024

  2. 980

  3. 1032

  4. 1280

  5. 2560
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D Correct answer
Explanation

This is a geometric progression with a = 5 and r = 2. The nth term is a * r^(n-1). The 9th term is 5 * 2^(9-1) = 5 * 2^8 = 5 * 256 = 1280.

AI explanation

The series follows a geometric progression where each term is multiplied by 2, making 2 the common ratio and 5 the first term. Using the formula for the nth term of a geometric progression, T9 = 5 * 2^(9-1) = 5 * 256 = 1280.

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