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Finding the Fourth Proportional to 390.77, 538.64 and 285.86

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Solution

The fourth proportional to 390.77, 538.64 and 285.86 is: 394.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.77 : 538.64 = 285.86 : x
  2. Step 2: Convert to fraction form
    390.77/538.64 = 285.86/x
  3. Step 3: Cross multiply
    390.77x = 538.64 × 285.86
  4. Step 4: Simplify right side
    390.77x = 153,976.62
  5. Step 5: Solve for x
    x = 153,976.62/390.77
  6. Step 6: Final answer
    x = 394.04

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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.