Tertiary activities, also known as the service sector, focus on providing services rather than producing goods. These activities require specialized skills, experience, and knowledge of workers because they often involve complex tasks and decision-making.
- Specialized skills are needed in fields such as healthcare, education, finance, and legal services, where expertise and qualifications are crucial for performing the tasks effectively.
- Experience plays an important role in many service-based industries. For instance, experienced professionals like doctors, teachers, or consultants provide a higher quality of service due to their practical understanding and ability to handle complex situations.
- Knowledge is a key component in sectors like information technology, research, and customer service, where workers need to stay updated with the latest trends, innovations, and regulations to perform their jobs effectively.
Thus, tertiary activities are largely dependent on the intellectual, technical, and professional abilities of workers who provide intangible services to society.

Standard electrode potential for \( \text{Sn}^{4+}/\text{Sn}^{2+} \) couple is +0.15 V and that for the \( \text{Cr}^{3+}/\text{Cr} \) couple is -0.74 V. The two couples in their standard states are connected to make a cell. The cell potential will be:
To calculate the cell potential (\( E^\circ_{\text{cell}} \)), we use the standard electrode potentials of the given redox couples.
Given data:
\( E^\circ_{\text{Sn}^{4+}/\text{Sn}^{2+}} = +0.15V \)
\( E^\circ_{\text{Cr}^{3+}/\text{Cr}} = -0.74V \)
A carpenter needs to make a wooden cuboidal box, closed from all sides, which has a square base and fixed volume. Since he is short of the paint required to paint the box on completion, he wants the surface area to be minimum.
On the basis of the above information, answer the following questions :
Find a relation between \( x \) and \( y \) such that the surface area \( S \) is minimum.
