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Finding the Fourth Proportional to 661.59, 990.86 and 387.60

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Solution

The fourth proportional to 661.59, 990.86 and 387.60 is: 580.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.59 : 990.86 = 387.60 : x
  2. Step 2: Convert to fraction form
    661.59/990.86 = 387.60/x
  3. Step 3: Cross multiply
    661.59x = 990.86 × 387.60
  4. Step 4: Simplify right side
    661.59x = 384,055.40
  5. Step 5: Solve for x
    x = 384,055.40/661.59
  6. Step 6: Final answer
    x = 580.50

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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.