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Finding the Fourth Proportional to 428.16, 642.21 and 120.03

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Solution

The fourth proportional to 428.16, 642.21 and 120.03 is: 180.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.16 : 642.21 = 120.03 : x
  2. Step 2: Convert to fraction form
    428.16/642.21 = 120.03/x
  3. Step 3: Cross multiply
    428.16x = 642.21 × 120.03
  4. Step 4: Simplify right side
    428.16x = 77,084.47
  5. Step 5: Solve for x
    x = 77,084.47/428.16
  6. Step 6: Final answer
    x = 180.04

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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.