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Finding the Fourth Proportional to 421.41, 632.15 and 128.90

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Solution

The fourth proportional to 421.41, 632.15 and 128.90 is: 193.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.41 : 632.15 = 128.90 : x
  2. Step 2: Convert to fraction form
    421.41/632.15 = 128.90/x
  3. Step 3: Cross multiply
    421.41x = 632.15 × 128.90
  4. Step 4: Simplify right side
    421.41x = 81,485.72
  5. Step 5: Solve for x
    x = 81,485.72/421.41
  6. Step 6: Final answer
    x = 193.36

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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.