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Finding the Fourth Proportional to 319.40, 479.60 and 257.91

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Solution

The fourth proportional to 319.40, 479.60 and 257.91 is: 387.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    319.40 : 479.60 = 257.91 : x
  2. Step 2: Convert to fraction form
    319.40/479.60 = 257.91/x
  3. Step 3: Cross multiply
    319.40x = 479.60 × 257.91
  4. Step 4: Simplify right side
    319.40x = 123,693.64
  5. Step 5: Solve for x
    x = 123,693.64/319.40
  6. Step 6: Final answer
    x = 387.27

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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.