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Finding the Fourth Proportional to 719.28, 990.63 and 640.17

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Solution

The fourth proportional to 719.28, 990.63 and 640.17 is: 881.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    719.28 : 990.63 = 640.17 : x
  2. Step 2: Convert to fraction form
    719.28/990.63 = 640.17/x
  3. Step 3: Cross multiply
    719.28x = 990.63 × 640.17
  4. Step 4: Simplify right side
    719.28x = 634,171.61
  5. Step 5: Solve for x
    x = 634,171.61/719.28
  6. Step 6: Final answer
    x = 881.68

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.