Solve the Case Study?

How do you solve this case study: "Estimate the number of  fish in all oceans together?"

• Please provide all the steps.

• Answer:

  These are typical estimate - gestimate questions asked in an interview. The whole point of asking these questions is to evaluate your though process. Generally you have to take some assumptions along the way. For this typical question I would go like this. We know that water is almost two-thirds on our planet. Hence the surface area should be 2/3 * earth's surface. Now I find out the average no. of fish that are present per cubic meter of volume. This can be figured by the general fishermen and the number of fish caught statistics. Again considering the average depth to be around y kms (which i ll find through a simple google search) I will get the volume of the water on earth. Further multiplying with the avg. number of fish per cubic meter I will get the number of fish in earth's water. I will add a buffer constant of c, just to convey that other factors such as habitat, required depth for fish presence, and others come into account. As said earlier there will be many approaches. You can find similar problems on the net. Hope this helps.