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Finding the Fourth Proportional to 391.10, 587.10 and 208.40

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Solution

The fourth proportional to 391.10, 587.10 and 208.40 is: 312.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.10 : 587.10 = 208.40 : x
  2. Step 2: Convert to fraction form
    391.10/587.10 = 208.40/x
  3. Step 3: Cross multiply
    391.10x = 587.10 × 208.40
  4. Step 4: Simplify right side
    391.10x = 122,351.64
  5. Step 5: Solve for x
    x = 122,351.64/391.10
  6. Step 6: Final answer
    x = 312.84

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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.