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Finding the Fourth Proportional to 320.40, 478.90 and 312.72

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Solution

The fourth proportional to 320.40, 478.90 and 312.72 is: 467.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    320.40 : 478.90 = 312.72 : x
  2. Step 2: Convert to fraction form
    320.40/478.90 = 312.72/x
  3. Step 3: Cross multiply
    320.40x = 478.90 × 312.72
  4. Step 4: Simplify right side
    320.40x = 149,761.61
  5. Step 5: Solve for x
    x = 149,761.61/320.40
  6. Step 6: Final answer
    x = 467.42

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.