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Finding the Fourth Proportional to 685.19, 1,027.79 and 319.78

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Solution

The fourth proportional to 685.19, 1,027.79 and 319.78 is: 479.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.19 : 1,027.79 = 319.78 : x
  2. Step 2: Convert to fraction form
    685.19/1,027.79 = 319.78/x
  3. Step 3: Cross multiply
    685.19x = 1,027.79 × 319.78
  4. Step 4: Simplify right side
    685.19x = 328,666.69
  5. Step 5: Solve for x
    x = 328,666.69/685.19
  6. Step 6: Final answer
    x = 479.67

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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.