Reasoning & Mental Ability

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Reasoning & Mental Ability — solved practice questions

8 WBCS General Mental Ability questions with step-by-step solutions. Attempt each, then reveal the answer.

1. Q1easy

   Find the next number in the series: 2, 4, 8, 16, ?

   • A32
   • B24
   • C30
   • D20
   Show answer & solution

   Correct answer: (A) 32

   Each term is double the previous one (2, 4, 8, 16), so the next term is 16 × 2 = 32.

2. Q2easy

   Find the next letter in the series: C, E, G, I, ?

   • AK
   • BJ
   • CL
   • DM
   Show answer & solution

   Correct answer: (A) K

   The letters advance by two positions each step (C→E→G→I), so the next letter is K.

3. Q3easy

   Which of the following numbers is the odd one out: 3, 5, 9, 11?

   • A9
   • B3
   • C5
   • D11
   Show answer & solution

   Correct answer: (A) 9

   3, 5 and 11 are prime numbers, whereas 9 = 3 × 3 is composite, making it the odd one out.

4. Q4easy

   Cat is to Kitten as Dog is to ?

   • APuppy
   • BCub
   • CCalf
   • DFoal
   Show answer & solution

   Correct answer: (A) Puppy

   A young cat is called a kitten and a young dog is called a puppy; the relation is animal to its young.

5. Q5medium

   In a certain code, CAT is written as DBU. How would DOG be written in the same code?

   • AEPH
   • BEPG
   • CDPG
   • DEQH
   Show answer & solution

   Correct answer: (A) EPH

   Each letter is shifted one place forward (C→D, A→B, T→U); applying the same shift to DOG gives E, P, H.

6. Q6medium

   Pointing to a photograph, a man said, "She is the daughter of my grandfather's only son." How is the woman in the photograph related to the man?

   • ASister
   • BMother
   • CAunt
   • DDaughter
   Show answer & solution

   Correct answer: (A) Sister

   The grandfather's only son is the man's own father, so the father's daughter is the man's sister.

7. Q7medium

   A man walks 5 km towards north, then turns right and walks 3 km, then turns right again and walks 5 km. How far is he from his starting point?

   • A3 km
   • B13 km
   • C8 km
   • D5 km
   Show answer & solution

   Correct answer: (A) 3 km

   Walking 5 km north, 3 km east and 5 km south brings him back to the starting latitude but 3 km to the east, so he is 3 km away.

8. Q8medium

   Find the missing number in the series: 3, 6, 11, 18, 27, ?

   • A38
   • B36
   • C40
   • D37
   Show answer & solution

   Correct answer: (A) 38

   The differences between terms increase by 2 (3, 5, 7, 9); adding the next difference 11 to 27 gives 38.

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