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Finding the Fourth Proportional to 428.51, 642.74 and 120.35

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Solution

The fourth proportional to 428.51, 642.74 and 120.35 is: 180.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.51 : 642.74 = 120.35 : x
  2. Step 2: Convert to fraction form
    428.51/642.74 = 120.35/x
  3. Step 3: Cross multiply
    428.51x = 642.74 × 120.35
  4. Step 4: Simplify right side
    428.51x = 77,350.55
  5. Step 5: Solve for x
    x = 77,350.55/428.51
  6. Step 6: Final answer
    x = 180.51

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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.