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Finding the Fourth Proportional to 390.92, 538.45 and 285.75

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Solution

The fourth proportional to 390.92, 538.45 and 285.75 is: 393.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.92 : 538.45 = 285.75 : x
  2. Step 2: Convert to fraction form
    390.92/538.45 = 285.75/x
  3. Step 3: Cross multiply
    390.92x = 538.45 × 285.75
  4. Step 4: Simplify right side
    390.92x = 153,861.37
  5. Step 5: Solve for x
    x = 153,861.37/390.92
  6. Step 6: Final answer
    x = 393.59

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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.