To determine how long it takes Heather to ring up 4 customers, we first need to find out how long it takes her to ring up one customer.
Heather can ring up 12 customers in 9 minutes. Therefore, the time it takes her to ring up one customer can be calculated as follows:
- Time per customer = Total time / Number of customers
- Time per customer = 9 minutes / 12 customers = 0.75 minutes per customer
Now, to find out how long it takes her to ring up 4 customers, we multiply the time it takes for one customer by 4:
- Time for 4 customers = Time per customer × 4
- Time for 4 customers = 0.75 minutes × 4 = 3 minutes
So, it takes Heather a total of 3 minutes to ring up 4 customers.