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Finding the Fourth Proportional to 428.86, 643.25 and 120.71

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Solution

The fourth proportional to 428.86, 643.25 and 120.71 is: 181.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.86 : 643.25 = 120.71 : x
  2. Step 2: Convert to fraction form
    428.86/643.25 = 120.71/x
  3. Step 3: Cross multiply
    428.86x = 643.25 × 120.71
  4. Step 4: Simplify right side
    428.86x = 77,642.89
  5. Step 5: Solve for x
    x = 77,642.89/428.86
  6. Step 6: Final answer
    x = 181.05

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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.