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Finding the Fourth Proportional to 679.59, 1,020.20 and 405.95

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Solution

The fourth proportional to 679.59, 1,020.20 and 405.95 is: 609.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.59 : 1,020.20 = 405.95 : x
  2. Step 2: Convert to fraction form
    679.59/1,020.20 = 405.95/x
  3. Step 3: Cross multiply
    679.59x = 1,020.20 × 405.95
  4. Step 4: Simplify right side
    679.59x = 414,143.06
  5. Step 5: Solve for x
    x = 414,143.06/679.59
  6. Step 6: Final answer
    x = 609.40

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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.