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Finding the Fourth Proportional to 1,280.78, 1,918.13 and 817.11

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Solution

The fourth proportional to 1,280.78, 1,918.13 and 817.11 is: 1,223.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.78 : 1,918.13 = 817.11 : x
  2. Step 2: Convert to fraction form
    1,280.78/1,918.13 = 817.11/x
  3. Step 3: Cross multiply
    1,280.78x = 1,918.13 × 817.11
  4. Step 4: Simplify right side
    1,280.78x = 1,567,322.18
  5. Step 5: Solve for x
    x = 1,567,322.18/1,280.78
  6. Step 6: Final answer
    x = 1,223.72

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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.