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Finding the Fourth Proportional to 420.66, 631.09 and 128.19

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Solution

The fourth proportional to 420.66, 631.09 and 128.19 is: 192.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.66 : 631.09 = 128.19 : x
  2. Step 2: Convert to fraction form
    420.66/631.09 = 128.19/x
  3. Step 3: Cross multiply
    420.66x = 631.09 × 128.19
  4. Step 4: Simplify right side
    420.66x = 80,900.00
  5. Step 5: Solve for x
    x = 80,900.00/420.66
  6. Step 6: Final answer
    x = 192.31

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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.