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Finding the Fourth Proportional to 661.38, 990.42 and 417.12

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Solution

The fourth proportional to 661.38, 990.42 and 417.12 is: 624.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.38 : 990.42 = 417.12 : x
  2. Step 2: Convert to fraction form
    661.38/990.42 = 417.12/x
  3. Step 3: Cross multiply
    661.38x = 990.42 × 417.12
  4. Step 4: Simplify right side
    661.38x = 413,123.99
  5. Step 5: Solve for x
    x = 413,123.99/661.38
  6. Step 6: Final answer
    x = 624.64

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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.