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Finding the Fourth Proportional to 421.78, 632.79 and 147.90

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Solution

The fourth proportional to 421.78, 632.79 and 147.90 is: 221.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.78 : 632.79 = 147.90 : x
  2. Step 2: Convert to fraction form
    421.78/632.79 = 147.90/x
  3. Step 3: Cross multiply
    421.78x = 632.79 × 147.90
  4. Step 4: Simplify right side
    421.78x = 93,589.64
  5. Step 5: Solve for x
    x = 93,589.64/421.78
  6. Step 6: Final answer
    x = 221.89

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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.