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Finding the Fourth Proportional to 840.21, 1,260.20 and 319.99

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Solution

The fourth proportional to 840.21, 1,260.20 and 319.99 is: 479.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.21 : 1,260.20 = 319.99 : x
  2. Step 2: Convert to fraction form
    840.21/1,260.20 = 319.99/x
  3. Step 3: Cross multiply
    840.21x = 1,260.20 × 319.99
  4. Step 4: Simplify right side
    840.21x = 403,251.40
  5. Step 5: Solve for x
    x = 403,251.40/840.21
  6. Step 6: Final answer
    x = 479.94

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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.