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Finding the Fourth Proportional to 660.60, 990.59 and 386.78

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Solution

The fourth proportional to 660.60, 990.59 and 386.78 is: 579.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.60 : 990.59 = 386.78 : x
  2. Step 2: Convert to fraction form
    660.60/990.59 = 386.78/x
  3. Step 3: Cross multiply
    660.60x = 990.59 × 386.78
  4. Step 4: Simplify right side
    660.60x = 383,133.51
  5. Step 5: Solve for x
    x = 383,133.51/660.60
  6. Step 6: Final answer
    x = 579.98

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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.