Question

how long does it take to ring up a customer with 20 items?
this graph shows how the time required to ring up a customer is related to the number of items being purchased.

Explanation:

Step1: Find the relationship between items and time

From the graph, we can see that when the number of items is \(100\), the time is \(600\) seconds. So the rate is \(\frac{600}{100}=6\) seconds per item.

Step2: Calculate the time for 20 items

Using the rate \(6\) seconds per item, for \(n = 20\) items, the time \(t=6\times20\)

Answer:

\(120\) seconds