Quantitative Aptitude – Sequence and series


Slot – 2 – Quantitative Aptitude – Sequence and series – The number of common terms in the two sequences

Q. The number of common terms in the two sequences: 15, 19, 23, 27, . . . . , 415 and 14, 19, 24, 29, . . . , 464 is?
  1. 18
  2. 19
  3. 21
  4. 20
Answer: 20

Solution: Common difference of first series 15, 19, 23, 27…= 4
Common difference of 2nd series 14, 19, 24, 29 .. =5
So common difference of the series formed by common terms = 4*5 = 20
First common term = 19
So series = 19, 39 , 59, … last term < 415
nth term = 19+20(n-1) = 20n – 1 < 415
so 20n < 416
n < 416/20 = 20.8
so n = 20

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