Reasoning : Logical Reasoning & Analytical Ability

Q 112 / 325

UPSC CSE Prelims 2021

You are given two identical sequences in two rows:

Sequence-I: 8 4 6 15 52.5 236.25
Sequence-II: 5 A B C D E

What is the entry in the place of C for the Sequence-II?

EXPLANATION

Correct Option (3)

The pattern in Sequence-I is established by multiplying each term by a progressively increasing factor. The factors begin at 0.5 and increase by 1.0 for each subsequent multiplication.

  • 8 × 0.5 = 4
  • 4 × 1.5 = 6
  • 6 × 2.5 = 15
  • 15 × 3.5 = 52.5
  • 52.5 × 4.5 = 236.25

Applying this identical pattern to Sequence-II, starting with the initial term 5:

  • A = 5 × 0.5 = 2.5
  • B = 2.5 × 1.5 = 3.75
  • C = 3.75 × 2.5 = 9.375

Thus, the entry in the place of C for Sequence-II is 9.375.

Incorrect Options:

  • Option 1 (2.5) corresponds to the value of A in Sequence-II (5 × 0.5 = 2.5), not C.
  • Option 2 (5) is the initial term of Sequence-II, not the value of C.
  • Option 4 (32.8125) corresponds to the value of D in Sequence-II (9.375 × 3.5 = 32.8125), not C.