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Finding the Fourth Proportional to 1,289.93, 1,780.00 and 765.86

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Solution

The fourth proportional to 1,289.93, 1,780.00 and 765.86 is: 1,056.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.93 : 1,780.00 = 765.86 : x
  2. Step 2: Convert to fraction form
    1,289.93/1,780.00 = 765.86/x
  3. Step 3: Cross multiply
    1,289.93x = 1,780.00 × 765.86
  4. Step 4: Simplify right side
    1,289.93x = 1,363,219.99
  5. Step 5: Solve for x
    x = 1,363,219.99/1,289.93
  6. Step 6: Final answer
    x = 1,056.82

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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.