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Finding the Fourth Proportional to 1,386.08, 1,912.32 and 861.92

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Solution

The fourth proportional to 1,386.08, 1,912.32 and 861.92 is: 1,189.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.08 : 1,912.32 = 861.92 : x
  2. Step 2: Convert to fraction form
    1,386.08/1,912.32 = 861.92/x
  3. Step 3: Cross multiply
    1,386.08x = 1,912.32 × 861.92
  4. Step 4: Simplify right side
    1,386.08x = 1,648,266.85
  5. Step 5: Solve for x
    x = 1,648,266.85/1,386.08
  6. Step 6: Final answer
    x = 1,189.16

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.