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Finding the Fourth Proportional to 428.21, 642.66 and 154.49

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Solution

The fourth proportional to 428.21, 642.66 and 154.49 is: 231.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.21 : 642.66 = 154.49 : x
  2. Step 2: Convert to fraction form
    428.21/642.66 = 154.49/x
  3. Step 3: Cross multiply
    428.21x = 642.66 × 154.49
  4. Step 4: Simplify right side
    428.21x = 99,287.51
  5. Step 5: Solve for x
    x = 99,287.51/428.21
  6. Step 6: Final answer
    x = 231.87

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.