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Finding the Fourth Proportional to 428.43, 642.29 and 172.11

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Solution

The fourth proportional to 428.43, 642.29 and 172.11 is: 258.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.43 : 642.29 = 172.11 : x
  2. Step 2: Convert to fraction form
    428.43/642.29 = 172.11/x
  3. Step 3: Cross multiply
    428.43x = 642.29 × 172.11
  4. Step 4: Simplify right side
    428.43x = 110,543.67
  5. Step 5: Solve for x
    x = 110,543.67/428.43
  6. Step 6: Final answer
    x = 258.02

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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.