There are many ways to solve this problem. For example, learners might calculate the time taken to process each size flask, add those times together, and then multiply by 3. Or, learners might calculate the time taken to clean each size flask, multiply those totals by 3, and then add the totals together. It is interesting to discuss the variety of ways to solve the problem, so this is a good problem to solve by groups of learners. This is also a conversion problem, if learners convert the minutes into hours.
Print this copy of the problem. It is interesting to see the images on the webpage, but learners may want to have this problem to do while away from the computer screen.