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Finding the Fourth Proportional to 1,280.78, 1,921.44 and 631.43

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Solution

The fourth proportional to 1,280.78, 1,921.44 and 631.43 is: 947.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.78 : 1,921.44 = 631.43 : x
  2. Step 2: Convert to fraction form
    1,280.78/1,921.44 = 631.43/x
  3. Step 3: Cross multiply
    1,280.78x = 1,921.44 × 631.43
  4. Step 4: Simplify right side
    1,280.78x = 1,213,254.86
  5. Step 5: Solve for x
    x = 1,213,254.86/1,280.78
  6. Step 6: Final answer
    x = 947.28

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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.