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Finding the Fourth Proportional to 645.16, 891.42 and 515.20

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Solution

The fourth proportional to 645.16, 891.42 and 515.20 is: 711.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.16 : 891.42 = 515.20 : x
  2. Step 2: Convert to fraction form
    645.16/891.42 = 515.20/x
  3. Step 3: Cross multiply
    645.16x = 891.42 × 515.20
  4. Step 4: Simplify right side
    645.16x = 459,259.58
  5. Step 5: Solve for x
    x = 459,259.58/645.16
  6. Step 6: Final answer
    x = 711.85

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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.