Numerical Ability Reviewer - Part 28

Practice 20 Numerical Ability questions for the Civil Service Exam (CSE), each with the correct answer and an explanation.

20 questions80% passing markFree

Part 28 of our Numerical Ability reviewer has 20 practice questions in the style of the Civil Service Exam. Answer them in order, read the explanation after each one, and check your score against the 80% passing mark at the end. Questions and choices are reshuffled every time you retake the part.

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Sample questions from Part 28

Here are a few questions from this part. Take the full test to answer all 20 and get your score.

Sample question 1

What is the value of 1/2 + 1/6 + 1/12 + 1/20 + 1/30?

  • 5/6
  • 6/7
  • 4/5
  • 31/30
Answer: 5/6
Each term is 1/[n(n+1)] = 1/n − 1/(n+1): 1/(1×2) + 1/(2×3) + 1/(3×4) + 1/(4×5) + 1/(5×6) = 1 − 1/6 = 5/6.

Sample question 2

Aling Nena spent 1/3 of her money on rent, then 1/4 of what remained on food. She had ₱18,000 left. How much money did she have at first?

  • ₱30,000
  • ₱42,000
  • ₱36,000
  • ₱27,000
Answer: ₱36,000
After rent: 2/3 remains. After food: 2/3 × 3/4 = 1/2 remains. If 1/2 of the money is ₱18,000, the original amount is ₱36,000.

Sample question 3

a : b = 3 : 4 and b : c = 6 : 5. If a + b + c = 124, what is c?

  • 45
  • 36
  • 40
  • 48
Answer: 40
Make b equal: a : b = 9 : 12 and b : c = 12 : 10, so a : b : c = 9 : 12 : 10 (sum 31). 124 ÷ 31 = 4. c = 10 × 4 = 40.

Sample question 4

What is the value of (3/4) ÷ (5/8 − 1/2)?

  • 6
  • 9/2
  • 3/32
  • 3/2
Answer: 6
5/8 − 1/2 = 1/8. Then (3/4) ÷ (1/8) = 3/4 × 8 = 6.

Sample question 5

Twelve workers can finish a road repair in 15 days. How many days will 9 workers (working at the same pace) need for the same job?

  • 18 days
  • 11.25 days
  • 12 days
  • 20 days
Answer: 20 days
More days are needed with fewer workers (inverse proportion). Work = 12 × 15 = 180 worker-days. 180 ÷ 9 = 20 days.

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