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Finding the Fourth Proportional to 985.20, 1,359.08 and 612.40

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Solution

The fourth proportional to 985.20, 1,359.08 and 612.40 is: 844.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.20 : 1,359.08 = 612.40 : x
  2. Step 2: Convert to fraction form
    985.20/1,359.08 = 612.40/x
  3. Step 3: Cross multiply
    985.20x = 1,359.08 × 612.40
  4. Step 4: Simplify right side
    985.20x = 832,300.59
  5. Step 5: Solve for x
    x = 832,300.59/985.20
  6. Step 6: Final answer
    x = 844.80

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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.