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Finding the Fourth Proportional to 1,020.75, 1,408.65 and 555

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Solution

The fourth proportional to 1,020.75, 1,408.65 and 555 is: 765.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,020.75 : 1,408.65 = 555 : x
  2. Step 2: Convert to fraction form
    1,020.75/1,408.65 = 555/x
  3. Step 3: Cross multiply
    1,020.75x = 1,408.65 × 555
  4. Step 4: Simplify right side
    1,020.75x = 781,798.67
  5. Step 5: Solve for x
    x = 781,798.67/1,020.75
  6. Step 6: Final answer
    x = 765.91

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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.