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Finding the Fourth Proportional to 319.90, 479.70 and 137.20

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Solution

The fourth proportional to 319.90, 479.70 and 137.20 is: 205.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    319.90 : 479.70 = 137.20 : x
  2. Step 2: Convert to fraction form
    319.90/479.70 = 137.20/x
  3. Step 3: Cross multiply
    319.90x = 479.70 × 137.20
  4. Step 4: Simplify right side
    319.90x = 65,814.84
  5. Step 5: Solve for x
    x = 65,814.84/319.90
  6. Step 6: Final answer
    x = 205.74

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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.