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Finding the Fourth Proportional to 645.28, 890.32 and 505.15

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Solution

The fourth proportional to 645.28, 890.32 and 505.15 is: 696.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.28 : 890.32 = 505.15 : x
  2. Step 2: Convert to fraction form
    645.28/890.32 = 505.15/x
  3. Step 3: Cross multiply
    645.28x = 890.32 × 505.15
  4. Step 4: Simplify right side
    645.28x = 449,745.15
  5. Step 5: Solve for x
    x = 449,745.15/645.28
  6. Step 6: Final answer
    x = 696.98

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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.