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 series: 7, 21, 63, 189,?
567
378
547
587
567
Observe that each term is exactly 3 times the preceding term (x3 multiplication series).
Observe that each term is exactly 3 times the preceding term (x3 multiplication series).
Analyze the pattern
Calculate the ratio between consecutive numbers: 21 / 7 = 3, 63 / 21 = 3, 189 / 63 = 3.
Calculate the missing term
Apply the identified multiplication factor (3) to the last term: 189 * 3 = 567.
B: 378 is incorrect as it results from adding 189 instead of multiplying by 3; C: 547 is mathematically inconsistent with the multiplication factor; D: 587 is not a multiple of 189.
A is correct because the series follows a geometric progression where each term is multiplied by 3 to obtain the next term, making 189 * 3 equal to 567.
For number series, always check the ratio between terms first. If the difference increases rapidly, it is likely a multiplication or power-based series rather than simple addition.