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Finding the Fourth Proportional to 318.78, 478.26 and 221.40

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Solution

The fourth proportional to 318.78, 478.26 and 221.40 is: 332.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.78 : 478.26 = 221.40 : x
  2. Step 2: Convert to fraction form
    318.78/478.26 = 221.40/x
  3. Step 3: Cross multiply
    318.78x = 478.26 × 221.40
  4. Step 4: Simplify right side
    318.78x = 105,886.76
  5. Step 5: Solve for x
    x = 105,886.76/318.78
  6. Step 6: Final answer
    x = 332.16

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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.