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Finding the Fourth Proportional to 3,128.50, 4,692.75 and 820

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Solution

The fourth proportional to 3,128.50, 4,692.75 and 820 is: 1,230

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,128.50 : 4,692.75 = 820 : x
  2. Step 2: Convert to fraction form
    3,128.50/4,692.75 = 820/x
  3. Step 3: Cross multiply
    3,128.50x = 4,692.75 × 820
  4. Step 4: Simplify right side
    3,128.50x = 3,848,055
  5. Step 5: Solve for x
    x = 3,848,055/3,128.50
  6. Step 6: Final answer
    x = 1,230

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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.