Sequence And Series Question 639
Question: Which number should be added to the numbers 13, 15, 19 so that the resulting numbers be the consecutive terms of a H.P.
Options:
A) 7
B) 6
C) $ -6 $
D) $ -7 $
Show Answer
Answer:
Correct Answer: D
Solution:
Suppose that $ x $ to be added then numbers 13, 15, 19 so that new numbers $ x+13,\ 15+x,\ 19+x $ will be in H.P.
$ \Rightarrow $ $ (15+x)=\frac{2(x+13)(19+x)}{x+13+x+19} $
$ \Rightarrow $ $ x^{2}+31x+240=x^{2}+32x+247\Rightarrow x=-7 $ Trick: Such type of questions should be checked with the options.
BETA
