Multiple choice

Which of the following terms of the series 7 + 11 + 15 … is equal to 403?

  1. 50

  2. 100

  3. 101

  4. 51
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is an arithmetic progression with a = 7 and d = 4. Formula: a_n = a + (n-1)d. 403 = 7 + (n-1)4. 396 = (n-1)4. 99 = n-1. n = 100.

AI explanation

The given series is an arithmetic progression with the first term a equal to 7 and a common difference d equal to 4. Using the formula for the nth term, Tn = a + (n - 1)d, we set Tn to 403, so 403 = 7 + (n - 1) times 4. Subtracting 7 gives 396, and dividing by 4 gives n - 1 = 99. Adding 1 means n equals 100.

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