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Finding the Fourth Proportional to 659.85, 990.11 and 428.68

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Solution

The fourth proportional to 659.85, 990.11 and 428.68 is: 643.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    659.85 : 990.11 = 428.68 : x
  2. Step 2: Convert to fraction form
    659.85/990.11 = 428.68/x
  3. Step 3: Cross multiply
    659.85x = 990.11 × 428.68
  4. Step 4: Simplify right side
    659.85x = 424,441.43
  5. Step 5: Solve for x
    x = 424,441.43/659.85
  6. Step 6: Final answer
    x = 643.24

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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.