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Finding the Fourth Proportional to 661.14, 990.80 and 386.86

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Solution

The fourth proportional to 661.14, 990.80 and 386.86 is: 579.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.14 : 990.80 = 386.86 : x
  2. Step 2: Convert to fraction form
    661.14/990.80 = 386.86/x
  3. Step 3: Cross multiply
    661.14x = 990.80 × 386.86
  4. Step 4: Simplify right side
    661.14x = 383,300.89
  5. Step 5: Solve for x
    x = 383,300.89/661.14
  6. Step 6: Final answer
    x = 579.76

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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.