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Finding the Fourth Proportional to 128.52, 177.36 and 76.80

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Solution

The fourth proportional to 128.52, 177.36 and 76.80 is: 105.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.52 : 177.36 = 76.80 : x
  2. Step 2: Convert to fraction form
    128.52/177.36 = 76.80/x
  3. Step 3: Cross multiply
    128.52x = 177.36 × 76.80
  4. Step 4: Simplify right side
    128.52x = 13,621.25
  5. Step 5: Solve for x
    x = 13,621.25/128.52
  6. Step 6: Final answer
    x = 105.99

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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.