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Finding the Fourth Proportional to 390.27, 538.57 and 215.61

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Solution

The fourth proportional to 390.27, 538.57 and 215.61 is: 297.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.27 : 538.57 = 215.61 : x
  2. Step 2: Convert to fraction form
    390.27/538.57 = 215.61/x
  3. Step 3: Cross multiply
    390.27x = 538.57 × 215.61
  4. Step 4: Simplify right side
    390.27x = 116,121.89
  5. Step 5: Solve for x
    x = 116,121.89/390.27
  6. Step 6: Final answer
    x = 297.54

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.