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Finding the Fourth Proportional to 1,272.15, 1,907.91 and 861.18

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Solution

The fourth proportional to 1,272.15, 1,907.91 and 861.18 is: 1,291.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,272.15 : 1,907.91 = 861.18 : x
  2. Step 2: Convert to fraction form
    1,272.15/1,907.91 = 861.18/x
  3. Step 3: Cross multiply
    1,272.15x = 1,907.91 × 861.18
  4. Step 4: Simplify right side
    1,272.15x = 1,643,053.93
  5. Step 5: Solve for x
    x = 1,643,053.93/1,272.15
  6. Step 6: Final answer
    x = 1,291.56

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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.