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Finding the Fourth Proportional to 128.95, 193.47 and 56.86

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Solution

The fourth proportional to 128.95, 193.47 and 56.86 is: 85.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.95 : 193.47 = 56.86 : x
  2. Step 2: Convert to fraction form
    128.95/193.47 = 56.86/x
  3. Step 3: Cross multiply
    128.95x = 193.47 × 56.86
  4. Step 4: Simplify right side
    128.95x = 11,000.70
  5. Step 5: Solve for x
    x = 11,000.70/128.95
  6. Step 6: Final answer
    x = 85.31

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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.