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Finding the Fourth Proportional to 128.94, 193.46 and 56.78

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Solution

The fourth proportional to 128.94, 193.46 and 56.78 is: 85.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.94 : 193.46 = 56.78 : x
  2. Step 2: Convert to fraction form
    128.94/193.46 = 56.78/x
  3. Step 3: Cross multiply
    128.94x = 193.46 × 56.78
  4. Step 4: Simplify right side
    128.94x = 10,984.66
  5. Step 5: Solve for x
    x = 10,984.66/128.94
  6. Step 6: Final answer
    x = 85.19

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.