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Finding the Fourth Proportional to 258.12, 386.94 and 87

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Solution

The fourth proportional to 258.12, 386.94 and 87 is: 130.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.12 : 386.94 = 87 : x
  2. Step 2: Convert to fraction form
    258.12/386.94 = 87/x
  3. Step 3: Cross multiply
    258.12x = 386.94 × 87
  4. Step 4: Simplify right side
    258.12x = 33,663.78
  5. Step 5: Solve for x
    x = 33,663.78/258.12
  6. Step 6: Final answer
    x = 130.42

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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.