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Finding the Fourth Proportional to 708.80, 978.15 and 398.30

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Solution

The fourth proportional to 708.80, 978.15 and 398.30 is: 549.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    708.80 : 978.15 = 398.30 : x
  2. Step 2: Convert to fraction form
    708.80/978.15 = 398.30/x
  3. Step 3: Cross multiply
    708.80x = 978.15 × 398.30
  4. Step 4: Simplify right side
    708.80x = 389,597.15
  5. Step 5: Solve for x
    x = 389,597.15/708.80
  6. Step 6: Final answer
    x = 549.66

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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.