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Finding the Fourth Proportional to 1,286.92, 1,776 and 789.40

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Solution

The fourth proportional to 1,286.92, 1,776 and 789.40 is: 1,089.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286.92 : 1,776 = 789.40 : x
  2. Step 2: Convert to fraction form
    1,286.92/1,776 = 789.40/x
  3. Step 3: Cross multiply
    1,286.92x = 1,776 × 789.40
  4. Step 4: Simplify right side
    1,286.92x = 1,401,974.40
  5. Step 5: Solve for x
    x = 1,401,974.40/1,286.92
  6. Step 6: Final answer
    x = 1,089.40

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Double scale
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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.