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Finding the Fourth Proportional to 861.12, 1,289.38 and 678.88

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Solution

The fourth proportional to 861.12, 1,289.38 and 678.88 is: 1,016.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.12 : 1,289.38 = 678.88 : x
  2. Step 2: Convert to fraction form
    861.12/1,289.38 = 678.88/x
  3. Step 3: Cross multiply
    861.12x = 1,289.38 × 678.88
  4. Step 4: Simplify right side
    861.12x = 875,334.29
  5. Step 5: Solve for x
    x = 875,334.29/861.12
  6. Step 6: Final answer
    x = 1,016.51

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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.