Hi there!
Since the store has an average of 90 seconds to process a sales transaction, this means that it takes, on average, 90 seconds per customer.
You want to know how much time will have passed when the last sales transaction is comlete, which is after 3 clients.
It takes 90 seconds for 1 customer, so in order to know how much time it takes for 3 customers you have to multiply the time it takes for one customer (90 seconds) by the number of customers in line (3) :
90 seconds × 3 customers = 270 seconds.
To convert 270 seconds into minutes, you need to divide the number of seconds (270) by 60 (because there are 60 seconds in 1 minute):
270 ÷ 60 = 4.5 minutes
Your answer is: a) 4.5 minutes will have passed when the last sales transaction is complete.
There you go! I really hope this helped, if there's anything just let me know! :)
