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Finding the Fourth Proportional to 651.80, 978.20 and 390.98

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Solution

The fourth proportional to 651.80, 978.20 and 390.98 is: 586.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    651.80 : 978.20 = 390.98 : x
  2. Step 2: Convert to fraction form
    651.80/978.20 = 390.98/x
  3. Step 3: Cross multiply
    651.80x = 978.20 × 390.98
  4. Step 4: Simplify right side
    651.80x = 382,456.64
  5. Step 5: Solve for x
    x = 382,456.64/651.80
  6. Step 6: Final answer
    x = 586.77

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.