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Finding the Fourth Proportional to 990.71, 1,487.21 and 580.14

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Solution

The fourth proportional to 990.71, 1,487.21 and 580.14 is: 870.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.71 : 1,487.21 = 580.14 : x
  2. Step 2: Convert to fraction form
    990.71/1,487.21 = 580.14/x
  3. Step 3: Cross multiply
    990.71x = 1,487.21 × 580.14
  4. Step 4: Simplify right side
    990.71x = 862,787.11
  5. Step 5: Solve for x
    x = 862,787.11/990.71
  6. Step 6: Final answer
    x = 870.88

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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.