Indian Navy SSR (Sailor) Arithmetic Progressions — practice questions

Explore 2 free Arithmetic Progressions questions in Indian Navy SSR (Sailor) Mathematics. Open each question or exercise to read its content, reference answers and available explanation.

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Arithmetic Progressions questions and exercises with answers

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If the last term is l, the sum of the first n terms of an AP is:Read the answer and worked solution →Find n if the nth term of the AP −1, 3, 7, … is 95.Read the answer and worked solution →

Worked practice questions

If the last term is l, the sum of the first n terms of an AP is:

$S_n = n(a + l)$
$S_n = \dfrac{n}{2}(a + l)$
$S_n = \dfrac{n}{2}(a - l)$
$S_n = \dfrac{n}{2}(a \times l)$

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Correct answer: B. $S_n = \dfrac{n}{2}(a + l)$

Using the last term l: Sₙ = n/2 (a + l).

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Find n if the nth term of the AP −1, 3, 7, … is 95.

n = 25
n = 26
n = 24
n = 23

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Correct answer: A. n = 25

a = −1, d = 4. aₙ = −1 + (n − 1)·4 = 95 ⇒ (n − 1)·4 = 96 ⇒ n − 1 = 24 ⇒ n = 25.