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Finding the Fourth Proportional to 985.76, 1,478.34 and 408.50

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Solution

The fourth proportional to 985.76, 1,478.34 and 408.50 is: 612.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.76 : 1,478.34 = 408.50 : x
  2. Step 2: Convert to fraction form
    985.76/1,478.34 = 408.50/x
  3. Step 3: Cross multiply
    985.76x = 1,478.34 × 408.50
  4. Step 4: Simplify right side
    985.76x = 603,901.89
  5. Step 5: Solve for x
    x = 603,901.89/985.76
  6. Step 6: Final answer
    x = 612.63

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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.