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Finding the Fourth Proportional to 128.75, 193.05 and 85.37

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Solution

The fourth proportional to 128.75, 193.05 and 85.37 is: 128.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.75 : 193.05 = 85.37 : x
  2. Step 2: Convert to fraction form
    128.75/193.05 = 85.37/x
  3. Step 3: Cross multiply
    128.75x = 193.05 × 85.37
  4. Step 4: Simplify right side
    128.75x = 16,479.71
  5. Step 5: Solve for x
    x = 16,479.71/128.75
  6. Step 6: Final answer
    x = 128.00

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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.