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Finding the Fourth Proportional to 839.78, 1,259.47 and 319.84

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Solution

The fourth proportional to 839.78, 1,259.47 and 319.84 is: 479.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.78 : 1,259.47 = 319.84 : x
  2. Step 2: Convert to fraction form
    839.78/1,259.47 = 319.84/x
  3. Step 3: Cross multiply
    839.78x = 1,259.47 × 319.84
  4. Step 4: Simplify right side
    839.78x = 402,822.59
  5. Step 5: Solve for x
    x = 402,822.59/839.78
  6. Step 6: Final answer
    x = 479.68

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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.