Quantitative Aptitude Ques 115

Question: The length of canvas 75 cm wide required to build a conical tent of height 14 m and the floor area $ 346.5,m^{2}, $ is

Options:

A) 665 m

B) 770 m

C) 490 m

D) 860 m

Show Answer

Answer:

Correct Answer: B

Solution:

  • Given, floor area $ 346.5m^{2} $

$ \therefore $ $ \pi r^{2}=346.5 $
$ \Rightarrow $ $ r^{2}=\frac{346.5}{22}\times 7 $

$ \Rightarrow $ $ r^{2}=11025 $
$ \Rightarrow $ $ r=10.5,m $ Now, $ l=\sqrt{r^{2}+h^{2}}=\sqrt{{{(10.5)}^{2}}+{{(14)}^{2}}} $ $ =\sqrt{110.25+196}=\sqrt{306.25}=17.5,m $

$ \therefore $ Area of canvas = Area of cone

$ \Rightarrow $ $ l\times b=\pi rl $

$ \Rightarrow $ $ l\times \frac{75}{100}=\frac{22}{7}\times 10.5\times 17.5 $

$ \Rightarrow $ $ l=\frac{22\times 10.5}{7\times 75}\times 17.5\times 100 $

$ \therefore $ $ l=770 $

$ \therefore $ Length of canvas = 770 m