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Finding the Fourth Proportional to 661.76, 987.64 and 644.48

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Solution

The fourth proportional to 661.76, 987.64 and 644.48 is: 961.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.76 : 987.64 = 644.48 : x
  2. Step 2: Convert to fraction form
    661.76/987.64 = 644.48/x
  3. Step 3: Cross multiply
    661.76x = 987.64 × 644.48
  4. Step 4: Simplify right side
    661.76x = 636,514.23
  5. Step 5: Solve for x
    x = 636,514.23/661.76
  6. Step 6: Final answer
    x = 961.85

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.