Subject: General Aptitude · Chapter: Volume and Surface Area · Exam: · Marks: · Difficulty:
A hemispherical bowls has 3.5cm radius. It is to be painted inside as well as outside. The cost of painting it at the rate of ₹ 5 per 10sq. cm will be [SSC-CHSL (10+2) Exam, 2015]
(a)₹ 77
(b)₹ 100
(c)₹ 175
(d)₹ 50
Answer
Answer (as printed): A
Explanation
Radius of a hemispherical bowl = 3.5cm Inner and outer surface areas of the bowl $=4 \pi r^{2}$ $$\begin{aligned} & =4 \times \frac{22}{7} \times 3.5 \times 3.5 \\ & =154 \text { sq. cm. } \end{aligned}$$ Total cost of painting at the rate of ₹ 5 per 10 sq. cm. $$=154 \times \frac{5}{10}=₹ 77$$
Explanation as extracted from the printed page; notation may be imperfect.