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Finding the Fourth Proportional to 320.40, 479.40 and 212.40

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Solution

The fourth proportional to 320.40, 479.40 and 212.40 is: 317.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    320.40 : 479.40 = 212.40 : x
  2. Step 2: Convert to fraction form
    320.40/479.40 = 212.40/x
  3. Step 3: Cross multiply
    320.40x = 479.40 × 212.40
  4. Step 4: Simplify right side
    320.40x = 101,824.56
  5. Step 5: Solve for x
    x = 101,824.56/320.40
  6. Step 6: Final answer
    x = 317.80

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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.