Solution :
The model is :
Year 1870 1871 1872 1873 1874 1875 1876
Population 365 384 393 392 381 360 329
It is given that a historian counted the number of people in the Gold Rush town for a 6 years staring from 1870.
Therefore the quadratic function which models a data as a function of the number of years from 1870 i.e. x is given by
And the number of people present the town of Gold Rush in the year 1878 can be found by using the model is 237.