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Finding the Fourth Proportional to 661.20, 990.78 and 487.59

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Solution

The fourth proportional to 661.20, 990.78 and 487.59 is: 730.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.20 : 990.78 = 487.59 : x
  2. Step 2: Convert to fraction form
    661.20/990.78 = 487.59/x
  3. Step 3: Cross multiply
    661.20x = 990.78 × 487.59
  4. Step 4: Simplify right side
    661.20x = 483,094.42
  5. Step 5: Solve for x
    x = 483,094.42/661.20
  6. Step 6: Final answer
    x = 730.63

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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.