Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Probability problem (came in TIFR)

  1. Sep 11, 2010 #1
    A marine biologist wanted to estimate the number of fish in a large lake. He threw a net and found 30 fish in the net. He marked all these fish and released them into the lake. The next morning he again threw the net and this time caught 40 fish, of which 2 were marked. The approximate number of fish in the lake is :
    a)600
    b)1200
    c)68
    d)800
    e)120
     
  2. jcsd
  3. Sep 11, 2010 #2

    statdad

    User Avatar
    Homework Helper

    The typical (introductory) way to attach this is to make this assumption:

    1) let P denote the fish population
    2) 30/P is the fraction of fish population marked with the first catch
    3) 2/40 is the fraction of the second catch found to be marked

    The assumption is that the two fractions are the same; solving for P gives the approximate population.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Probability problem (came in TIFR)
  1. Probability Problem (Replies: 3)

  2. Probability Problem (Replies: 1)

  3. Probability Problem (Replies: 1)

  4. Probability problem (Replies: 5)

Loading...