Home›MPPSC Prelims›Paper 2: General Aptitude Test (CSAT)›General Aptitude›Logical Reasoning and Analytical Ability›Deductive & Inductive Reasoning, Syllogisms, Series, Coding-Decoding›In the following number series, find out the wrong number : 2, 9, 18,

In the following number series, find out the wrong number :
2, 9, 18, 29, 43, 57, 74

20242Mprelimsyear-2024p2
A.(A) 9
B.(B) 43Correct
C.(C) 29
D.(D) 74
Explanation & Solution

The correct answer is (B) 43.

Step-by-step pattern analysis:

  • Examine the difference between consecutive terms:
  • 9−2=+79 - 2 = +79−2=+7
  • 18−9=+918 - 9 = +918−9=+9
  • 29−18=+1129 - 18 = +1129−18=+11
  • The pattern of differences consists of consecutive odd numbers (+7,+9,+11,+13,+15,+17+7, +9, +11, +13, +15, +17+7,+9,+11,+13,+15,+17).
  • Next term should be: 29+13=<strong>42</strong>29 + 13 = <strong>42</strong>29+13=<strong>42</strong> (instead of 43).
  • Verification: 42+15=5742 + 15 = 5742+15=57, and 57+17=7457 + 17 = 7457+17=74.
  • Therefore, the wrong number in the series is 43.

हिंदी में प्रश्न एवं आदर्श उत्तर

निम्नलिखित संख्या श्रृंखला में, गलत संख्या ज्ञात कीजिए :
2, 9, 18, 29, 43, 57, 74

A.(A) 9
B.(B) 43सही
C.(C) 29
D.(D) 74

सही उत्तर (B) 43 है।

चरणबद्ध श्रृंखला विश्लेषण:

  • क्रमिक पदों के अंतर की जाँच:
  • 9−2=+79 - 2 = +79−2=+7
  • 18−9=+918 - 9 = +918−9=+9
  • 29−18=+1129 - 18 = +1129−18=+11
  • श्रृंखला में क्रमिक विषम संख्याओं का अंतर (+7,+9,+11,+13,+15,+17+7, +9, +11, +13, +15, +17+7,+9,+11,+13,+15,+17) जुड़ रहा है।
  • अतः अगला पद 29+13=<strong>42</strong>29 + 13 = <strong>42</strong>29+13=<strong>42</strong> होना चाहिए (43 के स्थान पर)।
  • पुष्टि: 42+15=5742 + 15 = 5742+15=57, तथा 57+17=7457 + 17 = 7457+17=74।
  • अतः श्रृंखला में गलत संख्या 43 है।
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