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Finding the Fourth Proportional to 813.76, 1,220.40 and 683.80

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Solution

The fourth proportional to 813.76, 1,220.40 and 683.80 is: 1,025.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.76 : 1,220.40 = 683.80 : x
  2. Step 2: Convert to fraction form
    813.76/1,220.40 = 683.80/x
  3. Step 3: Cross multiply
    813.76x = 1,220.40 × 683.80
  4. Step 4: Simplify right side
    813.76x = 834,509.52
  5. Step 5: Solve for x
    x = 834,509.52/813.76
  6. Step 6: Final answer
    x = 1,025.50

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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.