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Finding the Fourth Proportional to 708.64, 978.01 and 398.20

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Solution

The fourth proportional to 708.64, 978.01 and 398.20 is: 549.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    708.64 : 978.01 = 398.20 : x
  2. Step 2: Convert to fraction form
    708.64/978.01 = 398.20/x
  3. Step 3: Cross multiply
    708.64x = 978.01 × 398.20
  4. Step 4: Simplify right side
    708.64x = 389,438.69
  5. Step 5: Solve for x
    x = 389,438.69/708.64
  6. Step 6: Final answer
    x = 549.56

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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.