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Finding the Fourth Proportional to 390.43, 538.79 and 215.77

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Solution

The fourth proportional to 390.43, 538.79 and 215.77 is: 297.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.43 : 538.79 = 215.77 : x
  2. Step 2: Convert to fraction form
    390.43/538.79 = 215.77/x
  3. Step 3: Cross multiply
    390.43x = 538.79 × 215.77
  4. Step 4: Simplify right side
    390.43x = 116,254.72
  5. Step 5: Solve for x
    x = 116,254.72/390.43
  6. Step 6: Final answer
    x = 297.76

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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.