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Finding the Fourth Proportional to 1,277.90, 1,918.12 and 861.38

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Solution

The fourth proportional to 1,277.90, 1,918.12 and 861.38 is: 1,292.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,277.90 : 1,918.12 = 861.38 : x
  2. Step 2: Convert to fraction form
    1,277.90/1,918.12 = 861.38/x
  3. Step 3: Cross multiply
    1,277.90x = 1,918.12 × 861.38
  4. Step 4: Simplify right side
    1,277.90x = 1,652,230.21
  5. Step 5: Solve for x
    x = 1,652,230.21/1,277.90
  6. Step 6: Final answer
    x = 1,292.93

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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.