Checkouts

When 4 checkouts are open in a supermarket, people wait in line for an average of 12 minutes. By how much does the waiting time increase when one checkout is closed?

Final Answer:

Δt =  4 min

Step-by-step explanation:

$$\begin{gathered} t_1=12\text{min} \\ {n}_1=4 \\ {n}_2=n_1-1=4-1=3 \\ T=n_1\cdot t_1=4\cdot 12=48\text{min} \\ {t}_2=T/n_2=48/3=16\text{min} \\ \Delta t=t_2-t_1=16-12=4\text{min} \end{gathered}$$

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