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Finding the Fourth Proportional to 978.85, 1,351.03 and 647.31

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Solution

The fourth proportional to 978.85, 1,351.03 and 647.31 is: 893.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.85 : 1,351.03 = 647.31 : x
  2. Step 2: Convert to fraction form
    978.85/1,351.03 = 647.31/x
  3. Step 3: Cross multiply
    978.85x = 1,351.03 × 647.31
  4. Step 4: Simplify right side
    978.85x = 874,535.23
  5. Step 5: Solve for x
    x = 874,535.23/978.85
  6. Step 6: Final answer
    x = 893.43

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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.