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Finding the Fourth Proportional to 421.32, 631.96 and 128.82

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Solution

The fourth proportional to 421.32, 631.96 and 128.82 is: 193.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.32 : 631.96 = 128.82 : x
  2. Step 2: Convert to fraction form
    421.32/631.96 = 128.82/x
  3. Step 3: Cross multiply
    421.32x = 631.96 × 128.82
  4. Step 4: Simplify right side
    421.32x = 81,409.09
  5. Step 5: Solve for x
    x = 81,409.09/421.32
  6. Step 6: Final answer
    x = 193.22

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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.