← General Intelligence and Reasoning

Series — Questions with Solutions

11 solved Series questions from General Intelligence and Reasoning, as asked in SSC CGL and other SSC exams. Read the answer and explanation below, then practise the full set in the practice section.

Practise this topic

Q1. Which of the following numbers will replace the question mark (?) in the given series? 1, 3, 10, 41, ?, 1237

  1. A. 210
  2. B. 202
  3. C. 206
  4. D. 200

Solution

The pattern is: 1*2+1=3; 3*3+1=10; 10*4+1=41; 41*5+1=206; 206*6+1=1237.

Q2. Select the option that represents the letters that when placed from left to right in the blanks below will complete the given letter series. LMBA_HOLMBAC_OLM_ACHOL_BACHOL_

उस विकल्प का चयन करें जो रिक्त स्थानों में बाएँ से दाएँ रखे जाने पर दी गई अक्षर श्रृंखला को पूरा करेगा। LMBA_HOLMBAC_OLM_ACHOL_BACHOL_

  1. A. CHMBM
  2. B. CMHBM
  3. C. CHBMM
  4. D. CHMMB

Solution

The repeating series is 'LMBACHOL'. Filling the blanks with C, H, M, B, M completes the pattern perfectly.

Q3. Which letter-cluster will replace the question mark (?) to complete the given series? ZVRN, VSPM, RPNL, ?, JJJJ

दी गई श्रृंखला को पूरा करने के लिए प्रश्नवाचक चिह्न (?) को कौन सा अक्षर-समूह प्रतिस्थापित करेगा? ZVRN, VSPM, RPNL, ?, JJJJ

  1. A. RMLN
  2. B. RNLL
  3. C. RNLK
  4. D. NMLK

Solution

First letters: Z(-4)=V(-4)=R(-4)=N. Second: V(-3)=S(-3)=P(-3)=M. Third: R(-2)=P(-2)=N(-2)=L. Fourth: N(-1)=M(-1)=L(-1)=K. Result is NMLK.

Q4. Select the number from among the given options that can replace the question mark (?) in the following series. $23, 27, 43, 79, 143, ?$

दिए गए विकल्पों में से उस संख्या का चयन करें जो श्रृंखला में प्रश्नवाचक चिह्न (?) को प्रतिस्थापित कर सकती है। $23, 27, 43, 79, 143, ?$

  1. A. $240$
  2. B. $243$
  3. C. $250$
  4. D. $200$

Solution

Differences between terms are consecutive even squares: $+4 (2^2), +16 (4^2), +36 (6^2), +64 (8^2)$. Next difference is $+100 (10^2)$. $143 + 100 = 243$.

Q5. Select the option that can replace the question mark (?) in the following series. FM61, EK58, DI55, CG52, ?

उस विकल्प का चयन करें जो निम्नलिखित श्रृंखला में प्रश्नवाचक चिह्न (?) को प्रतिस्थापित कर सकता है। FM61, EK58, DI55, CG52, ?

  1. A. BE49
  2. B. CE46
  3. C. CD44
  4. D. BF48

Solution

First letters: F(-1)=E(-1)=D(-1)=C(-1)=B. Second: M(-2)=K(-2)=I(-2)=G(-2)=E. Numbers: 61(-3)=58(-3)=55(-3)=52(-3)=49. Thus, BE49.

Q6. Select the letter-cluster that can replace the question mark (?) in the following series. AZ, CX, EV, ?

निम्नलिखित श्रृंखला में प्रश्न चिह्न (?) को प्रतिस्थापित करने वाले अक्षर-समूह का चयन करें। AZ, CX, EV, ?

  1. A. GT
  2. B. HS
  3. C. GS
  4. D. FT

Solution

The first letter of each cluster increases by 2 (A, C, E, G). The second letter is the reverse alphabetical pair of the first letter (Z, X, V, T). So, GT is the correct answer.

Q7. Which number will replace the question mark (?) in the following series? 5, 11, 24, 51, 106, ?

निम्नलिखित श्रृंखला में प्रश्न चिह्न (?) के स्थान पर कौन सी संख्या आएगी? 5, 11, 24, 51, 106, ?

  1. A. 217
  2. B. 212
  3. C. 220
  4. D. 215

Solution

The logic is $x \times 2 + 1, x \times 2 + 2, x \times 2 + 3...$ For the last term: $106 \times 2 + 5 = 217$.

Q8. Select the number from among the given options that can replace the question mark (?) in the following series. 99, 123, 150, 180, 213, ?

  1. A. 259
  2. B. 258
  3. C. 248
  4. D. 249

Solution

The differences between consecutive terms are: 123-99=24, 150-123=27, 180-150=30, 213-180=33. The next difference should be 36. So, 213 + 36 = 249.

Q9. Select the option that can replace the question mark (?) in the following series. VO39, TM35, RK31, PI27, ?

  1. A. OH24
  2. B. NG23
  3. C. MH24
  4. D. MG22

Solution

First letters: V (-2) -> T (-2) -> R (-2) -> P (-2) -> N. Second letters: O (-2) -> M (-2) -> K (-2) -> I (-2) -> G. Numbers: 39 (-4) -> 35 (-4) -> 31 (-4) -> 27 (-4) -> 23. Combining them gives NG23.

Q10. Select the option that represents the letters that when placed from left to right in the blanks below will complete the given letter series. N_BANA_A_ANANAB_NANABA_ANA

  1. A. ANANB
  2. B. NANAB
  3. C. ANABN
  4. D. ANBAN

Solution

The series repeats the pattern 'NABANA'. Filling in the blanks with N, A, N, A, B correctly completes the cyclical sequence.

Q11. Select the letter-cluster from among the given options that can replace the question mark (?) to complete the given series. BVTO, DTVM, ?, HPZI, JNBG

  1. A. RXFK
  2. B. RFXK
  3. C. FKXR
  4. D. FRXK

Solution

First letters: B(+2)=D(+2)=F. Second letters: V(-2)=T(-2)=R. Third letters: T(+2)=V(+2)=X. Fourth letters: O(-2)=M(-2)=K. The resulting cluster is FRXK.