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Finding the Fourth Proportional to 708.75, 978.14 and 398.31

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Solution

The fourth proportional to 708.75, 978.14 and 398.31 is: 549.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    708.75 : 978.14 = 398.31 : x
  2. Step 2: Convert to fraction form
    708.75/978.14 = 398.31/x
  3. Step 3: Cross multiply
    708.75x = 978.14 × 398.31
  4. Step 4: Simplify right side
    708.75x = 389,600.95
  5. Step 5: Solve for x
    x = 389,600.95/708.75
  6. Step 6: Final answer
    x = 549.70

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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.