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Finding the Fourth Proportional to 258.45, 387.64 and 85.13

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Solution

The fourth proportional to 258.45, 387.64 and 85.13 is: 127.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.45 : 387.64 = 85.13 : x
  2. Step 2: Convert to fraction form
    258.45/387.64 = 85.13/x
  3. Step 3: Cross multiply
    258.45x = 387.64 × 85.13
  4. Step 4: Simplify right side
    258.45x = 32,997.43
  5. Step 5: Solve for x
    x = 32,997.43/258.45
  6. Step 6: Final answer
    x = 127.67

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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.