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Finding the Fourth Proportional to 985.60, 1,478.40 and 408.32

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Solution

The fourth proportional to 985.60, 1,478.40 and 408.32 is: 612.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.60 : 1,478.40 = 408.32 : x
  2. Step 2: Convert to fraction form
    985.60/1,478.40 = 408.32/x
  3. Step 3: Cross multiply
    985.60x = 1,478.40 × 408.32
  4. Step 4: Simplify right side
    985.60x = 603,660.29
  5. Step 5: Solve for x
    x = 603,660.29/985.60
  6. Step 6: Final answer
    x = 612.48

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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.