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Finding the Fourth Proportional to 1,223.20, 1,687.98 and 663.64

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Solution

The fourth proportional to 1,223.20, 1,687.98 and 663.64 is: 915.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,223.20 : 1,687.98 = 663.64 : x
  2. Step 2: Convert to fraction form
    1,223.20/1,687.98 = 663.64/x
  3. Step 3: Cross multiply
    1,223.20x = 1,687.98 × 663.64
  4. Step 4: Simplify right side
    1,223.20x = 1,120,211.05
  5. Step 5: Solve for x
    x = 1,120,211.05/1,223.20
  6. Step 6: Final answer
    x = 915.80

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.