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TCS NQT GuideTCS NQT Numerical AbilityArithmetic and Geometric Progressions (AP & GP) Series

Arithmetic and Geometric Progressions (AP & GP) Series

Learn core concepts, essential formulas, and attempt practice questions designed on the latest TCS NQT testing patterns.

Key Concepts & Formulas

  • 1AP Term: Tn = a + (n-1)d, where a is first term, d is difference.
  • 2AP Sum: Sn = n/2 * [2a + (n-1)d].
  • 3GP Term: Tn = a * r^(n-1), where r is common ratio.
  • 4GP Sum: Sn = a * (r^n - 1) / (r - 1) for r>1.
  • 5Infinite GP Sum: S_inf = a / (1-r) for r<1.

TCS NQT Style Practice Questions

Practice Question 1

Find the 10th term of the AP: 3, 7, 11, 15...

A) 39
B) 43
C) 35
D) 41

Correct Answer: A) 39

Step-by-step Solution: Here a = 3, d = 4. T_10 = a + 9d = 3 + 9(4) = 3 + 36 = 39.

Practice Question 2

Find the sum of the infinite GP: 1, 1/2, 1/4, 1/8...

A) 2
B) 1.5
C) Infinite
D) 3

Correct Answer: A) 2

Step-by-step Solution: Here a = 1, r = 1/2. S_inf = a / (1 - r) = 1 / (1 - 0.5) = 2.

Study Pro-Tip

Infinite GP sums are heavily tested in quantitative papers. Master the S_inf = a / (1-r) formula.

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