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Finding the Fourth Proportional to 687.26, 947.94 and 421.72

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Solution

The fourth proportional to 687.26, 947.94 and 421.72 is: 581.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.26 : 947.94 = 421.72 : x
  2. Step 2: Convert to fraction form
    687.26/947.94 = 421.72/x
  3. Step 3: Cross multiply
    687.26x = 947.94 × 421.72
  4. Step 4: Simplify right side
    687.26x = 399,761.31
  5. Step 5: Solve for x
    x = 399,761.31/687.26
  6. Step 6: Final answer
    x = 581.67

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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.