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Finding the Fourth Proportional to 390.13, 538.40 and 215.47

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Solution

The fourth proportional to 390.13, 538.40 and 215.47 is: 297.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.13 : 538.40 = 215.47 : x
  2. Step 2: Convert to fraction form
    390.13/538.40 = 215.47/x
  3. Step 3: Cross multiply
    390.13x = 538.40 × 215.47
  4. Step 4: Simplify right side
    390.13x = 116,007.97
  5. Step 5: Solve for x
    x = 116,007.97/390.13
  6. Step 6: Final answer
    x = 297.36

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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.