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Finding the Fourth Proportional to 665.80, 918.35 and 438.55

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Solution

The fourth proportional to 665.80, 918.35 and 438.55 is: 604.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.80 : 918.35 = 438.55 : x
  2. Step 2: Convert to fraction form
    665.80/918.35 = 438.55/x
  3. Step 3: Cross multiply
    665.80x = 918.35 × 438.55
  4. Step 4: Simplify right side
    665.80x = 402,745.78
  5. Step 5: Solve for x
    x = 402,745.78/665.80
  6. Step 6: Final answer
    x = 604.90

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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.