Subject: General Aptitude · Chapter: Volume and Surface Area · Exam: · Marks: · Difficulty:
What will be the total cost of whitewashing the coni- cal tomb at the rate of 80 paise per square metre? I. The diameter and the slant height of the tomb are 28 m and 50 m. II. The height of the tomb is 48 m and the area of its base is 616 sq. m.
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.
Explanation
I. gives, $r=14 \mathrm{m}, l=50 \mathrm{m}$. $\therefore$ Curved surface $=\pi r l=\left(\frac{22}{7} \times 14 \times 50\right) \mathrm{m}^{2}=2200 \mathrm{m}^{2}$. Cost of whitewashing $=₹\left(2200 \times \frac{80}{100}\right)=₹ 1760$. Thus, I alone gives the answer. II. gives, $h=48 \mathrm{m}, \pi r^{2}=616 \mathrm{m}^{2}$. These results give $r$ and $h$ and so $l$ can be found out. $\therefore$ Curved surface $=\pi r l$. Thus, II alone gives the answer. $\therefore$ Correct answer is (c).