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Finding the Fourth Proportional to 390.20, 538.45 and 215.54

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Solution

The fourth proportional to 390.20, 538.45 and 215.54 is: 297.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.20 : 538.45 = 215.54 : x
  2. Step 2: Convert to fraction form
    390.20/538.45 = 215.54/x
  3. Step 3: Cross multiply
    390.20x = 538.45 × 215.54
  4. Step 4: Simplify right side
    390.20x = 116,057.51
  5. Step 5: Solve for x
    x = 116,057.51/390.20
  6. Step 6: Final answer
    x = 297.43

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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.