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Finding the Fourth Proportional to 860.92, 1,289.60 and 420.85

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Solution

The fourth proportional to 860.92, 1,289.60 and 420.85 is: 630.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.92 : 1,289.60 = 420.85 : x
  2. Step 2: Convert to fraction form
    860.92/1,289.60 = 420.85/x
  3. Step 3: Cross multiply
    860.92x = 1,289.60 × 420.85
  4. Step 4: Simplify right side
    860.92x = 542,719.61
  5. Step 5: Solve for x
    x = 542,719.61/860.92
  6. Step 6: Final answer
    x = 630.39

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Double scale
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1.5x scale

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.