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Finding the Fourth Proportional to 128.21, 175.78 and 125.78

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Solution

The fourth proportional to 128.21, 175.78 and 125.78 is: 172.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.21 : 175.78 = 125.78 : x
  2. Step 2: Convert to fraction form
    128.21/175.78 = 125.78/x
  3. Step 3: Cross multiply
    128.21x = 175.78 × 125.78
  4. Step 4: Simplify right side
    128.21x = 22,109.61
  5. Step 5: Solve for x
    x = 22,109.61/128.21
  6. Step 6: Final answer
    x = 172.45

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.