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Finding the Fourth Proportional to 680.34, 1,020.78 and 420.60

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Solution

The fourth proportional to 680.34, 1,020.78 and 420.60 is: 631.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.34 : 1,020.78 = 420.60 : x
  2. Step 2: Convert to fraction form
    680.34/1,020.78 = 420.60/x
  3. Step 3: Cross multiply
    680.34x = 1,020.78 × 420.60
  4. Step 4: Simplify right side
    680.34x = 429,340.07
  5. Step 5: Solve for x
    x = 429,340.07/680.34
  6. Step 6: Final answer
    x = 631.07

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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.