Multiple choice

Directions: Answer the questions independently of each other. The number of common term in two sequence 17, 21, 25……., 417 and 16, 21, 26……466 is

  1. 25

  2. 40

  3. 20

  4. 12
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sequence 1: 17, 21, 25, ..., 417 (a=17, d=4). Sequence 2: 16, 21, 26, ..., 466 (a=16, d=5). Common terms start at 21 and follow an AP with d = LCM(4,5) = 20. Terms are 21, 41, ..., 401. 401 = 21 + (n-1)20, so 380 = (n-1)20, n-1 = 19, n = 20.

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