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Finding the Fourth Proportional to 641.45, 960.39 and 421.40

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Solution

The fourth proportional to 641.45, 960.39 and 421.40 is: 630.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.45 : 960.39 = 421.40 : x
  2. Step 2: Convert to fraction form
    641.45/960.39 = 421.40/x
  3. Step 3: Cross multiply
    641.45x = 960.39 × 421.40
  4. Step 4: Simplify right side
    641.45x = 404,710.75
  5. Step 5: Solve for x
    x = 404,710.75/641.45
  6. Step 6: Final answer
    x = 630.93

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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.