Subject: General Aptitude · Chapter: Volume and Surface Area · Exam: · Marks: · Difficulty:
What is the total cost of painting the in- ner surface of an open box at the rate of 50 paise per 100 sq. cm? I. The box is made of wood 3 cm thick. II. The external dimensions of the box are 50 cm, 40 cm and 23 cm.
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.
Explanation
I. gives, thickness of the wall of the box = 3 cm. II. gives, Internal length $=(50-6) \mathrm{cm}=44 \mathrm{cm}$, Internal breadth $=(40-6)=34 \mathrm{cm}$, Internal height $=(23-3) \mathrm{cm}=20 \mathrm{cm}$. Area to be painted = (area of 4 walls + area of floor) $=[2(l+b) \times h+(l \times b)]$ $=[2(44+34) \times 20+(44 \times 34)] \mathrm{cm}^{2}=4616 \mathrm{cm}^{2}$. Cost of painting $=₹\left(\frac{1}{2 \times 100} \times 4616\right)=₹ 23.08$.