In a city, the following weekly observations were made in a study of cost of living index for the year 1980-81.
Calculate the mean weekly cost of living index by a suitable method.

In a city, the following weekly observations were made in a study on cost of living index : Draw a histogram and frequency polygon for the above data on the same graph.

In a city, the weekly observations made in a study on the cost of living index are given in the following table: Draw a frequency polygon for the data above (without constructing a histogram).

Draw a histogram and a frequency polygon in represent the following data, which shows the montly cost of living index of a city in a period of 2 years

In the chemical analysis of a rock the mass ratio of two radioactive isotopes is found to be 100:1. The mean lives of the two isotopes are 4xx10^9 years and 2xx10^9 years, respectively. If it is assumed that at the time of formation the atoms of both the isotopes were in equal propotional, calculate the age of the rock. Ratio of the atomic weights of the two isotopes is 1.02:1.