A coffee maker makes coffee by passing steam through a mixture of coffee powder, milk and water. If the steam is mixed at the rate of $50\,\text{g}$ per minute in a mug containing $500\,\text{g}$ of mixture, then it takes about $t_0$ seconds to make coffee at $70^\circ\text{C}$ when the initial temperature of the mixture is $25^\circ\text{C}$. The value of $t_0$ is close to (ratio of latent heat of evaporation to specific heat of water is $540^\circ\text{C}$ and specific heat of the mixture can be taken to be the same as that of water)