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Finding the Fourth Proportional to 805.80, 1,206.90 and 420.60

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Solution

The fourth proportional to 805.80, 1,206.90 and 420.60 is: 629.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    805.80 : 1,206.90 = 420.60 : x
  2. Step 2: Convert to fraction form
    805.80/1,206.90 = 420.60/x
  3. Step 3: Cross multiply
    805.80x = 1,206.90 × 420.60
  4. Step 4: Simplify right side
    805.80x = 507,622.14
  5. Step 5: Solve for x
    x = 507,622.14/805.80
  6. Step 6: Final answer
    x = 629.96

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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.