Maths Olympiad
Exam
Numerical Ability
three numbers in GP are such that their product is 216 if the sum of product in pairs is 156 then the numbers are
Read Solution (Total 2)
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- ans is 2,618
a=2,r=3 - 10 years agoHelpfull: Yes(1) No(0)
- i) Let the 3 numbers in GP be a/r, a & ar
ii) So their product is: (a/r)*(a)*(ar) = a^3 = 216; ==> a = 6
iii) As such the 3 numbers are: 6/r, 6, 6r
iv) As per the second constraint: (6/r)*(6) + 6*6r + (6r)*(6/r) = 156
Taking LCM, simplifying and rearranging, 3r² - 10r + 3 = 0
Factorizing, (3r - 1)(r - 3) = 0
==> Either r = 3 or r = 1/3
As both are feasible solutions, substituting these in (iii), we get
the 3 numbers as: {2, 6, 18} or {18, 6, 2}
EDIT:
In the final answer, the second triplet was {18, 6, 1}, which is now corrected as
{18, 6, 2} - 8 years agoHelpfull: Yes(0) No(0)
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