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Finding the Fourth Proportional to 679.47, 1,017.68 and 415.20

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Solution

The fourth proportional to 679.47, 1,017.68 and 415.20 is: 621.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.47 : 1,017.68 = 415.20 : x
  2. Step 2: Convert to fraction form
    679.47/1,017.68 = 415.20/x
  3. Step 3: Cross multiply
    679.47x = 1,017.68 × 415.20
  4. Step 4: Simplify right side
    679.47x = 422,538.66
  5. Step 5: Solve for x
    x = 422,538.66/679.47
  6. Step 6: Final answer
    x = 621.87

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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.