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Finding the Fourth Proportional to 708.99, 978.40 and 398.49

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Solution

The fourth proportional to 708.99, 978.40 and 398.49 is: 549.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    708.99 : 978.40 = 398.49 : x
  2. Step 2: Convert to fraction form
    708.99/978.40 = 398.49/x
  3. Step 3: Cross multiply
    708.99x = 978.40 × 398.49
  4. Step 4: Simplify right side
    708.99x = 389,880.62
  5. Step 5: Solve for x
    x = 389,880.62/708.99
  6. Step 6: Final answer
    x = 549.91

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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.