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Finding the Fourth Proportional to 428.63, 642.95 and 172.13

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Solution

The fourth proportional to 428.63, 642.95 and 172.13 is: 258.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.63 : 642.95 = 172.13 : x
  2. Step 2: Convert to fraction form
    428.63/642.95 = 172.13/x
  3. Step 3: Cross multiply
    428.63x = 642.95 × 172.13
  4. Step 4: Simplify right side
    428.63x = 110,666.91
  5. Step 5: Solve for x
    x = 110,666.91/428.63
  6. Step 6: Final answer
    x = 258.19

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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.