Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
What should come in place of the question mark (?) in the given series? 1 13 28 46 67 ?
90
92
93
91
91
Calculate the first-order differences between terms: +12, +15, +18, +21. Notice they increase by 3 each time. Add 24 to 67 to get 91 immediately.
Calculate the first-order differences between terms: +12, +15, +18, +21. Notice they increase by 3 each time. Add 24 to 67 to get 91 immediately.
Calculate First-Order Differences
Find the difference between consecutive terms in the series: 13 - 1 = 12, 28 - 13 = 15, 46 - 28 = 18, 67 - 46 = 21.
Identify Second-Order Pattern
Examine the sequence of differences (12, 15, 18, 21): 15 - 12 = +3, 18 - 15 = +3, 21 - 18 = +3. The differences form an Arithmetic Progression (AP) increasing by +3 at each step.
Calculate the Missing Term
The next difference must be 21 + 3 = 24. Adding 24 to the last given term (67) yields 67 + 24 = 91.
A: 90 is incorrect because 67 + 23 = 90 (violates the +3 difference rule). B: 92 is incorrect because 67 + 25 = 92. C: 93 is incorrect because 67 + 26 = 93.
D is correct because adding the next increment of 24 (from the AP difference pattern +12, +15, +18, +21, +24) to 67 gives exactly 91.
When terms increase gradually without huge jumps, always check the first and second differences first before trying square/cube or multiplicative patterns.
Get instant step-by-step AI explanations, full shift Previous Year Papers (SSC GD, RRB, SSC JE), and regional rank analysis on the official Examoogle App.
Free Download тАв 100K+ Aspirants