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Finding the Fourth Proportional to 680.90, 1,021.37 and 420.74

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Solution

The fourth proportional to 680.90, 1,021.37 and 420.74 is: 631.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.90 : 1,021.37 = 420.74 : x
  2. Step 2: Convert to fraction form
    680.90/1,021.37 = 420.74/x
  3. Step 3: Cross multiply
    680.90x = 1,021.37 × 420.74
  4. Step 4: Simplify right side
    680.90x = 429,727.16
  5. Step 5: Solve for x
    x = 429,727.16/680.90
  6. Step 6: Final answer
    x = 631.12

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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.