# Quantitative Ability (Part 9 of 9)

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- Let S denote the infinite sum 2 + 5x + 9 × 2 + 14 × 3 + 20 × 4 + ________, where|x|< 1 and the coefficient of xn-1 is n (n + 3) (n = 1,2, …) , Then S equals
- 2 − x/ (1 − x) 3
- 2 − x/ (1 + x) 3
- 2 + x/ (1 − x) 3
- 2 + x/ (1 + x) 3

Answer: a

- ABCD is a rectangle. The points p and Q lie on AD and AB respectively. If the triangles PAQ, QBC and PCD all have the same areas and BQ = 2, then AQ =
- 1 + v5
- 1 − v5
- v7
- 2v7

Answer: a

- For which value of k does the following pair of equations yield a unique solution for x such that the solution is positive? x2 − y2 = 0 (x-k) 2 + y2 = 1
- 2
- 0
- v2
- -v2

Answer: c

- In an examination, the average marks obtained by students who passed was x % , while the average of those who failed was y % . The average marks of all students taking the exam was z % . Find in terms of x, y and z, the percentage of students taking the exam who failed.
- (z-x) / (y-x)
- (x-z) / (y-z)
- (y-x) / (z-y)
- (y-z) / (x-z)

Answer: a