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Finding the Fourth Proportional to 645.20, 889.68 and 561.57

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Solution

The fourth proportional to 645.20, 889.68 and 561.57 is: 774.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.20 : 889.68 = 561.57 : x
  2. Step 2: Convert to fraction form
    645.20/889.68 = 561.57/x
  3. Step 3: Cross multiply
    645.20x = 889.68 × 561.57
  4. Step 4: Simplify right side
    645.20x = 499,617.60
  5. Step 5: Solve for x
    x = 499,617.60/645.20
  6. Step 6: Final answer
    x = 774.36

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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.