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Finding the Fourth Proportional to 125.21, 172.81 and 81.00

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Solution

The fourth proportional to 125.21, 172.81 and 81.00 is: 111.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    125.21 : 172.81 = 81.00 : x
  2. Step 2: Convert to fraction form
    125.21/172.81 = 81.00/x
  3. Step 3: Cross multiply
    125.21x = 172.81 × 81.00
  4. Step 4: Simplify right side
    125.21x = 13,997.84
  5. Step 5: Solve for x
    x = 13,997.84/125.21
  6. Step 6: Final answer
    x = 111.80

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.