Quantitative Aptitude Ques 804
Question: If $ P=\frac{1}{25}, $ then value of $ 125p^{3}-\frac{1}{64}-\frac{75}{4}p^{2}+\frac{15}{16}p $ is equal to
Options:
A) $ \frac{-1}{8000} $
B) $ \frac{1}{8000} $
C) $ \frac{1}{2000} $
D) $ \frac{-1}{2000} $
Show Answer
Answer:
Correct Answer: A
Solution:
- $ P=\frac{1}{25} $
Now, $ 125p^{3}-\frac{1}{64}-\frac{75}{4}p^{2}+\frac{15}{16}p $
$ ={{(5p)}^{3}}-{{( \frac{1}{4} )}^{3}}-\frac{3\times 25}{4}p^{2}+\frac{3\times 5}{4^{2}}p $
$ ={{( 5p-\frac{1}{4} )}^{3}} $
On putting $ p=\frac{1}{25}, $ we get
$ {{( 5\times \frac{1}{25}-\frac{1}{4} )}^{3}}={{( \frac{1}{5}-\frac{1}{4} )}^{3}} $
$ =( \frac{-1}{20} )=\frac{-1}{8000} $