Miscellaneous Question 45
- Quantity I : Value of
Sum of Single digit positive odd integers Sum of Single digit positive even integers
Quantity II : Value of
Sum of cubes of Single digit positive odd integers Sum of cubes of Single digit positive even integers
(1) Quantity I > Quantity II
(2) Quantity I $<$ Quantity II
(3) Quantity I $\leq$ Quantity II
(4) Quantity I $\geq$ Quantity II
(5) Quantity I = Quantity II or No relation.
(IBPS Bank PO/MT CWE (Main Exam) 26.11.2017)
Show Answer
Correct Answer: 45. (2)
Solution: 45. (2) I :
value $=\frac{1+3+5+7+9}{2+4+6+8}=\frac{25}{20}$
$=\frac{5}{4}=\frac{40}{32}$
II :
value $=\frac{1^{3}+3^{3}+5^{3}+7^{3}+9^{3}}{2^{3}+4^{3}+6^{3}+8^{3}}$
$=\frac{5^{2}\left(2 \times 5^{2}-1\right)}{2(4 \times 5)^{2}}=\frac{25 \times 49}{2 \times 400}=\frac{49}{32}$
$\therefore$ Quantity I $<$ Quantity II
Note :
(i) Sum of cubes of first $\mathrm{n}$ odd natural numbers $=n^{2}\left(2 n^{2}-1\right)$
(ii) Sum of cubes of first $n$ even natural numbers $=2[n(n+1)]^{2}$
(iii) Sum of first $n$ natural numbers $=\frac{n(n+1)}{2}$
(iv) Sum of first $n$ odd natural numbers $=n^{2}$
(v) Sum of first $n$ even natural numbers $=n(n+1)$