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Finding the Fourth Proportional to 390.09, 585.40 and 287.63

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Solution

The fourth proportional to 390.09, 585.40 and 287.63 is: 431.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.09 : 585.40 = 287.63 : x
  2. Step 2: Convert to fraction form
    390.09/585.40 = 287.63/x
  3. Step 3: Cross multiply
    390.09x = 585.40 × 287.63
  4. Step 4: Simplify right side
    390.09x = 168,376.85
  5. Step 5: Solve for x
    x = 168,376.85/390.09
  6. Step 6: Final answer
    x = 431.63

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.