I often find minimum + ensure questions confusing, so I’ve attached two examples. The first is from PP Plus Test 2, where we’re asked how many pencils Ben must select to ensure he has at least 2 of each color. If the question had asked for at least 2 of the same color, would he only need to pick 6 pencils?? In the worst-case scenario, if he picks 5 differently colored pencils, selecting one more guarantees that he has at least 2 of the same color. Can someone confirm this?
In the next question, I initially thought I needed to remove 10 or 11 socks to guarantee 2 of the same color, but I realized it only required 2 of any color, not each. What is the general approach for solving these types of questions? Do we always consider the worst-case scenario to find the minimum? Where can I find more practice questions?
Thanks!
