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Finding the Fourth Proportional to 258.68, 387.90 and 91.85

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Solution

The fourth proportional to 258.68, 387.90 and 91.85 is: 137.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.68 : 387.90 = 91.85 : x
  2. Step 2: Convert to fraction form
    258.68/387.90 = 91.85/x
  3. Step 3: Cross multiply
    258.68x = 387.90 × 91.85
  4. Step 4: Simplify right side
    258.68x = 35,628.63
  5. Step 5: Solve for x
    x = 35,628.63/258.68
  6. Step 6: Final answer
    x = 137.73

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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.