HP Missing Term

Harmonic Progression (HP) missing term problems present a sequence of numbers whose reciprocals form an arithmetic progression. You must find the missing term by converting to AP, finding the missing reciprocal, then converting back.

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200+Practice Questions
AdvancedDifficulty
3-4 hoursHours to Master

Introduction to HP Missing Term

Harmonic Progression (HP) missing term problems present a sequence of numbers whose reciprocals form an arithmetic progression. You must find the missing term by converting to AP, finding the missing reciprocal, then converting back.

Prerequisites

Harmonic Progression concept HP = reciprocal of AP AP missing term methods Fraction operations
Why This Matters: HP missing term problems appear in 1-2 questions in advanced exams like CAT and banking mains. They test understanding of HP-AP relationships.

How to Solve HP Missing Term Problems

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Step 1: Take reciprocals of all given HP terms to get an AP

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Step 2: Find the missing term in this AP using AP methods

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Step 3: Take the reciprocal of the AP missing term

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Step 4: This reciprocal is the missing HP term

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Step 5: Verify by checking the original HP sequence

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Step 6: Present the missing HP term

Pro Strategy: Always convert HP to AP by taking reciprocals first. Solve the AP problem, then convert back by taking reciprocal of the answer.

Example Problem

Example: Find the missing term in HP: 1/2, 1/5, 1/8, ?, 1/14 Solution: Step 1: Reciprocals: 2, 5, 8, _, 14 (this is an AP) Step 2: AP common difference d = 5-2 = 3 Step 3: Next term: 8 + 3 = 11 Step 4: Check: 11 + 3 = 14 ✓ Step 5: Missing HP term = 1/11 Answer: 1/11

Pro Tips & Tricks

  • HP of the form: 1/a, 1/(a+d), 1/(a+2d), ...
  • Three terms in HP: a, b, c satisfy 2/b = 1/a + 1/c
  • The harmonic mean of a and c is 2ac/(a+c)
  • If a, b, c are in HP, then 1/a, 1/b, 1/c are in AP
  • Always check if terms are positive (HP usually defined for positive numbers)
  • For fractions, take reciprocal carefully

Shortcut Methods to Solve Faster

If a, b, c are in HP, then b = 2ac/(a+c)
Reciprocals form AP: 1/a, 1/b, 1/c
Convert to AP, solve, then convert back

Common Mistakes to Avoid

Forgetting to take reciprocals
Taking reciprocal of the wrong term
Applying AP formulas directly to HP without conversion
Not verifying that terms are positive

Exam Importance

HP Missing Term is an important topic for various competitive exams. Here's how frequently it appears:

SSC CGL
0-1 questions
BANKING PO
0-1 questions
RAILWAYS RRB
0-1 questions
CAT
1-2 questions
INSURANCE
0-1 questions

Ready to Master HP Missing Term?

Start with Worksheet 1 and work your way up to expert level! Each worksheet includes:

20 practice questions
Detailed solutions
Step-by-step explanations
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