The amount of a specific bacteria in a culture, $B$, is modelled by the formula

$$B=p{q}^t$$

where $p$ and $q$ are constants and $t$ is the number of hours after the measurement began at 12:00 PM. A graph of ${\log }_{10}B$ against $t$ is plotted based on data from the first 4 hours. The data points follow a straight line with a gradient of 0.12 and a vertical intercept on the ${\log }_{10}B$ axis of 1.45.