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Finding the Fourth Proportional to 1,280.76, 1,921.50 and 459

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Solution

The fourth proportional to 1,280.76, 1,921.50 and 459 is: 688.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.76 : 1,921.50 = 459 : x
  2. Step 2: Convert to fraction form
    1,280.76/1,921.50 = 459/x
  3. Step 3: Cross multiply
    1,280.76x = 1,921.50 × 459
  4. Step 4: Simplify right side
    1,280.76x = 881,968.50
  5. Step 5: Solve for x
    x = 881,968.50/1,280.76
  6. Step 6: Final answer
    x = 688.63

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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.