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Finding the Fourth Proportional to 320.40, 442.20 and 278.80

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Solution

The fourth proportional to 320.40, 442.20 and 278.80 is: 384.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    320.40 : 442.20 = 278.80 : x
  2. Step 2: Convert to fraction form
    320.40/442.20 = 278.80/x
  3. Step 3: Cross multiply
    320.40x = 442.20 × 278.80
  4. Step 4: Simplify right side
    320.40x = 123,285.36
  5. Step 5: Solve for x
    x = 123,285.36/320.40
  6. Step 6: Final answer
    x = 384.79

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.