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Finding the Fourth Proportional to 661.76, 990.86 and 429.98

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Solution

The fourth proportional to 661.76, 990.86 and 429.98 is: 643.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.76 : 990.86 = 429.98 : x
  2. Step 2: Convert to fraction form
    661.76/990.86 = 429.98/x
  3. Step 3: Cross multiply
    661.76x = 990.86 × 429.98
  4. Step 4: Simplify right side
    661.76x = 426,049.98
  5. Step 5: Solve for x
    x = 426,049.98/661.76
  6. Step 6: Final answer
    x = 643.81

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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.