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Finding the Fourth Proportional to 990.81, 1,487.57 and 638.46

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Solution

The fourth proportional to 990.81, 1,487.57 and 638.46 is: 958.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.81 : 1,487.57 = 638.46 : x
  2. Step 2: Convert to fraction form
    990.81/1,487.57 = 638.46/x
  3. Step 3: Cross multiply
    990.81x = 1,487.57 × 638.46
  4. Step 4: Simplify right side
    990.81x = 949,753.94
  5. Step 5: Solve for x
    x = 949,753.94/990.81
  6. Step 6: Final answer
    x = 958.56

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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.