About This Set
This set is a step up, closer to Tier 2. Most questions need two steps or a careful setup: a chain of joinings and replacements, two groups that overlap, or a group size hidden behind three averages. Write each total down as you go rather than holding it in your head. The [Tier 2] items go beyond what Tier 1 usually asks, so if you are preparing only for Tier 1 you can come back to them later. Take about 35 minutes and read the explanations at the end. If you get 18 or more right, you can handle averages at exam level.