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Finding the Fourth Proportional to 428.13, 642.20 and 103.50

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Solution

The fourth proportional to 428.13, 642.20 and 103.50 is: 155.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.13 : 642.20 = 103.50 : x
  2. Step 2: Convert to fraction form
    428.13/642.20 = 103.50/x
  3. Step 3: Cross multiply
    428.13x = 642.20 × 103.50
  4. Step 4: Simplify right side
    428.13x = 66,467.57
  5. Step 5: Solve for x
    x = 66,467.57/428.13
  6. Step 6: Final answer
    x = 155.25

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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.