Sequences & Progressions

medium importance~1 Q in Tier 123 formulas⚡ 15 shortcuts5 subtopics

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Exam-level questions worked step by step. Try each one yourself first — then expand the solution and compare routes.

Q1.

A hall has 18 rows of chairs. The first row has 15 chairs and each row has 3 more chairs than the previous one. How many chairs are there in the hall?

Q2.

Three numbers in GP have a sum of 21 and a product of 216. The numbers are:

Q3.

The sum of the infinite GP $9 + 3 + 1 + \dfrac{1}{3} + \cdots$ is:

Q4.

Which term of the HP $\dfrac{1}{2}, \dfrac{1}{5}, \dfrac{1}{8}, \ldots$ is $\dfrac{1}{32}$ ?

Q5.

Find the sum $\dfrac{1}{1 \cdot 2} + \dfrac{1}{2 \cdot 3} + \dfrac{1}{3 \cdot 4} + \cdots + \dfrac{1}{9 \cdot 10}$ .

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