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Finding the Fourth Proportional to 645.72, 889.88 and 505.61

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Solution

The fourth proportional to 645.72, 889.88 and 505.61 is: 696.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.72 : 889.88 = 505.61 : x
  2. Step 2: Convert to fraction form
    645.72/889.88 = 505.61/x
  3. Step 3: Cross multiply
    645.72x = 889.88 × 505.61
  4. Step 4: Simplify right side
    645.72x = 449,925.25
  5. Step 5: Solve for x
    x = 449,925.25/645.72
  6. Step 6: Final answer
    x = 696.78

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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.