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Finding the Fourth Proportional to 1,386.13, 1,912.53 and 861.88

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Solution

The fourth proportional to 1,386.13, 1,912.53 and 861.88 is: 1,189.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.13 : 1,912.53 = 861.88 : x
  2. Step 2: Convert to fraction form
    1,386.13/1,912.53 = 861.88/x
  3. Step 3: Cross multiply
    1,386.13x = 1,912.53 × 861.88
  4. Step 4: Simplify right side
    1,386.13x = 1,648,371.36
  5. Step 5: Solve for x
    x = 1,648,371.36/1,386.13
  6. Step 6: Final answer
    x = 1,189.19

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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.