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Finding the Fourth Proportional to 1,289.76, 1,930.20 and 878.40

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Solution

The fourth proportional to 1,289.76, 1,930.20 and 878.40 is: 1,314.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.76 : 1,930.20 = 878.40 : x
  2. Step 2: Convert to fraction form
    1,289.76/1,930.20 = 878.40/x
  3. Step 3: Cross multiply
    1,289.76x = 1,930.20 × 878.40
  4. Step 4: Simplify right side
    1,289.76x = 1,695,487.68
  5. Step 5: Solve for x
    x = 1,695,487.68/1,289.76
  6. Step 6: Final answer
    x = 1,314.58

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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.