Darren wanted to see how contagious yawning can be. To better understand this, he conducted a social experiment in which he yawned in front of a large, random crowd and observed how many people yawned as a result.

The relationship between the elapsed time ${t}$, in minutes, since Darren yawned, and the number of people in the crowd, ${P}({t})$, who yawned as a result is modeled by the following function: $P(t)=5 \cdot(4)^{\frac{t}{10.5}}$

Complete the following sentence about the growth rate of people who yawned in Darren’s experiment.

The number of people who yawned quadruples (is multiplied by 4) every minutes.