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Finding the Fourth Proportional to 827.21, 1,239.45 and 387.99

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Solution

The fourth proportional to 827.21, 1,239.45 and 387.99 is: 581.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    827.21 : 1,239.45 = 387.99 : x
  2. Step 2: Convert to fraction form
    827.21/1,239.45 = 387.99/x
  3. Step 3: Cross multiply
    827.21x = 1,239.45 × 387.99
  4. Step 4: Simplify right side
    827.21x = 480,894.21
  5. Step 5: Solve for x
    x = 480,894.21/827.21
  6. Step 6: Final answer
    x = 581.35

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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.