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Finding the Fourth Proportional to 258.38, 387.63 and 85.05

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Solution

The fourth proportional to 258.38, 387.63 and 85.05 is: 127.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.38 : 387.63 = 85.05 : x
  2. Step 2: Convert to fraction form
    258.38/387.63 = 85.05/x
  3. Step 3: Cross multiply
    258.38x = 387.63 × 85.05
  4. Step 4: Simplify right side
    258.38x = 32,967.93
  5. Step 5: Solve for x
    x = 32,967.93/258.38
  6. Step 6: Final answer
    x = 127.60

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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.