Question

Three grams of soil were added to 27 ml of sterile water and shaken vigorously. After the soil particles settled, 0.1 ml of this was added to 9.9 ml of sterile water. This was further diluted by 4 successive 1/10 dilutions. One ml from the last dilution was used to prepare a pour plate. After incubation, 289 colonies were present on this plate. What was the number of colony-forming units/gram of the soil?

Answer 1

Three houses are available in a locality. three persons apply for the houses. each applies for one house without consulting others. the probability that all the three apply for the same house is