A medium question on queues for P2–P4, with a step-by-step solution, diagrams and the answer. Queue questions are already in the Hua Xia Cup's P1 and P2 first rounds, and the P4 papers add square formations.
The question
At assembly the class stands in a rectangle: several rows with the same number of children in each.
Ming is in the 3rd row from the front and the 3rd row from the back.
In his row he is 2nd from the left and 10th from the right.
How many children are in the class?
Show the hints (2)
💡Hint 1: First look front to back only: how many rows are there?
💡Hint 2: Then count Ming's row. In both directions, Ming gets counted twice.
Worked solution
Have a go first, then read the solution step by step.
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