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Finding the Fourth Proportional to 390.36, 538.62 and 312.92

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Solution

The fourth proportional to 390.36, 538.62 and 312.92 is: 431.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.36 : 538.62 = 312.92 : x
  2. Step 2: Convert to fraction form
    390.36/538.62 = 312.92/x
  3. Step 3: Cross multiply
    390.36x = 538.62 × 312.92
  4. Step 4: Simplify right side
    390.36x = 168,544.97
  5. Step 5: Solve for x
    x = 168,544.97/390.36
  6. Step 6: Final answer
    x = 431.77

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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.