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Finding the Fourth Proportional to 698.86, 1,047.98 and 211.78

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Solution

The fourth proportional to 698.86, 1,047.98 and 211.78 is: 317.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    698.86 : 1,047.98 = 211.78 : x
  2. Step 2: Convert to fraction form
    698.86/1,047.98 = 211.78/x
  3. Step 3: Cross multiply
    698.86x = 1,047.98 × 211.78
  4. Step 4: Simplify right side
    698.86x = 221,941.20
  5. Step 5: Solve for x
    x = 221,941.20/698.86
  6. Step 6: Final answer
    x = 317.58

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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.