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Finding the Fourth Proportional to 257.86, 386.72 and 75.21

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Solution

The fourth proportional to 257.86, 386.72 and 75.21 is: 112.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.86 : 386.72 = 75.21 : x
  2. Step 2: Convert to fraction form
    257.86/386.72 = 75.21/x
  3. Step 3: Cross multiply
    257.86x = 386.72 × 75.21
  4. Step 4: Simplify right side
    257.86x = 29,085.21
  5. Step 5: Solve for x
    x = 29,085.21/257.86
  6. Step 6: Final answer
    x = 112.79

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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.