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Finding the Fourth Proportional to 125.21, 172.68 and 81.50

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Solution

The fourth proportional to 125.21, 172.68 and 81.50 is: 112.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    125.21 : 172.68 = 81.50 : x
  2. Step 2: Convert to fraction form
    125.21/172.68 = 81.50/x
  3. Step 3: Cross multiply
    125.21x = 172.68 × 81.50
  4. Step 4: Simplify right side
    125.21x = 14,073.42
  5. Step 5: Solve for x
    x = 14,073.42/125.21
  6. Step 6: Final answer
    x = 112.40

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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.