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Finding the Fourth Proportional to 665.15, 918.71 and 487.85

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Solution

The fourth proportional to 665.15, 918.71 and 487.85 is: 673.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.15 : 918.71 = 487.85 : x
  2. Step 2: Convert to fraction form
    665.15/918.71 = 487.85/x
  3. Step 3: Cross multiply
    665.15x = 918.71 × 487.85
  4. Step 4: Simplify right side
    665.15x = 448,190.23
  5. Step 5: Solve for x
    x = 448,190.23/665.15
  6. Step 6: Final answer
    x = 673.82

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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.