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Finding the Fourth Proportional to 661.48, 990.86 and 642.04

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Solution

The fourth proportional to 661.48, 990.86 and 642.04 is: 961.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.48 : 990.86 = 642.04 : x
  2. Step 2: Convert to fraction form
    661.48/990.86 = 642.04/x
  3. Step 3: Cross multiply
    661.48x = 990.86 × 642.04
  4. Step 4: Simplify right side
    661.48x = 636,171.75
  5. Step 5: Solve for x
    x = 636,171.75/661.48
  6. Step 6: Final answer
    x = 961.74

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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.