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Finding the Fourth Proportional to 258.19, 387.28 and 87.19

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Solution

The fourth proportional to 258.19, 387.28 and 87.19 is: 130.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.19 : 387.28 = 87.19 : x
  2. Step 2: Convert to fraction form
    258.19/387.28 = 87.19/x
  3. Step 3: Cross multiply
    258.19x = 387.28 × 87.19
  4. Step 4: Simplify right side
    258.19x = 33,766.08
  5. Step 5: Solve for x
    x = 33,766.08/258.19
  6. Step 6: Final answer
    x = 130.78

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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.