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Finding the Fourth Proportional to 679.78, 1,019.85 and 217.57

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Solution

The fourth proportional to 679.78, 1,019.85 and 217.57 is: 326.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.78 : 1,019.85 = 217.57 : x
  2. Step 2: Convert to fraction form
    679.78/1,019.85 = 217.57/x
  3. Step 3: Cross multiply
    679.78x = 1,019.85 × 217.57
  4. Step 4: Simplify right side
    679.78x = 221,888.76
  5. Step 5: Solve for x
    x = 221,888.76/679.78
  6. Step 6: Final answer
    x = 326.41

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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.