A school hall has 22 seats in the first row, and each row has 3 seats more than the row in front of…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A school hall has seats in the first row, and each row has seats more than the row in front of it. There are rows. How many seats are in the last row?
Need a reminder? The key ideaShow
With two terms given, subtract them to find (the number of steps is the difference of the term numbers), then find . Three numbers in an AP: , , , with sum . To count numbers of a kind, find the first and the last and solve for .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The AP. seats.
Step 2. The last row. .
Answer: The last row has seats.
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