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Finding the Fourth Proportional to 1,005.75, 1,387.22 and 612.80

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Solution

The fourth proportional to 1,005.75, 1,387.22 and 612.80 is: 845.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,005.75 : 1,387.22 = 612.80 : x
  2. Step 2: Convert to fraction form
    1,005.75/1,387.22 = 612.80/x
  3. Step 3: Cross multiply
    1,005.75x = 1,387.22 × 612.80
  4. Step 4: Simplify right side
    1,005.75x = 850,078.42
  5. Step 5: Solve for x
    x = 850,078.42/1,005.75
  6. Step 6: Final answer
    x = 845.22

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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.