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Finding the Fourth Proportional to 680.60, 1,020.08 and 420.18

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Solution

The fourth proportional to 680.60, 1,020.08 and 420.18 is: 629.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.60 : 1,020.08 = 420.18 : x
  2. Step 2: Convert to fraction form
    680.60/1,020.08 = 420.18/x
  3. Step 3: Cross multiply
    680.60x = 1,020.08 × 420.18
  4. Step 4: Simplify right side
    680.60x = 428,617.21
  5. Step 5: Solve for x
    x = 428,617.21/680.60
  6. Step 6: Final answer
    x = 629.76

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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.