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Finding the Fourth Proportional to 680.34, 1,020.82 and 420.74

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Solution

The fourth proportional to 680.34, 1,020.82 and 420.74 is: 631.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.34 : 1,020.82 = 420.74 : x
  2. Step 2: Convert to fraction form
    680.34/1,020.82 = 420.74/x
  3. Step 3: Cross multiply
    680.34x = 1,020.82 × 420.74
  4. Step 4: Simplify right side
    680.34x = 429,499.81
  5. Step 5: Solve for x
    x = 429,499.81/680.34
  6. Step 6: Final answer
    x = 631.30

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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.