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Finding the Fourth Proportional to 985.50, 1,478.25 and 408.39

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Solution

The fourth proportional to 985.50, 1,478.25 and 408.39 is: 612.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.50 : 1,478.25 = 408.39 : x
  2. Step 2: Convert to fraction form
    985.50/1,478.25 = 408.39/x
  3. Step 3: Cross multiply
    985.50x = 1,478.25 × 408.39
  4. Step 4: Simplify right side
    985.50x = 603,702.52
  5. Step 5: Solve for x
    x = 603,702.52/985.50
  6. Step 6: Final answer
    x = 612.59

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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.