Number System Ques 28
Question
There are 6 consecutive odd numbers. The square of the average of the last three numbers is 386 more than the product of the first two numbers. What is the value of the first odd number?
(1) 25
(2) 23
(3) 27
(4) 29
(5) 21
IBPS Bank PO/MT CWE (Prelim Exam) 19.10.2019
Show Answer
Answer: (2)
Solution: (2)
6 consecutive odd numbers
$\Rightarrow x, x+2, x+4, x+6, x+8$ and $x+10$
According to the question,
$\left(\frac{x+6+x+8+x+10}{3}\right)^{2}$ $=x(x+2)+386$
$\Rightarrow\left(\frac{3 x+24}{3}\right)^{2}=x^{2}+2 x+386$
$\Rightarrow(x+8)^{2}=x^{2}+2 x+386$
$\Rightarrow x^{2}+16 x+64=x^{2}+2 x+386$
$\Rightarrow 16 x-2 x=386-64$
$\Rightarrow 14 x=322$
$\Rightarrow x=\frac{322}{14}=23$
BETA
