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Finding the Fourth Proportional to 659.97, 990.31 and 428.81

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Solution

The fourth proportional to 659.97, 990.31 and 428.81 is: 643.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    659.97 : 990.31 = 428.81 : x
  2. Step 2: Convert to fraction form
    659.97/990.31 = 428.81/x
  3. Step 3: Cross multiply
    659.97x = 990.31 × 428.81
  4. Step 4: Simplify right side
    659.97x = 424,654.83
  5. Step 5: Solve for x
    x = 424,654.83/659.97
  6. Step 6: Final answer
    x = 643.45

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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.