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Finding the Fourth Proportional to 665.60, 998.40 and 391.55

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Solution

The fourth proportional to 665.60, 998.40 and 391.55 is: 587.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.60 : 998.40 = 391.55 : x
  2. Step 2: Convert to fraction form
    665.60/998.40 = 391.55/x
  3. Step 3: Cross multiply
    665.60x = 998.40 × 391.55
  4. Step 4: Simplify right side
    665.60x = 390,923.52
  5. Step 5: Solve for x
    x = 390,923.52/665.60
  6. Step 6: Final answer
    x = 587.33

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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.