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Finding the Fourth Proportional to 979.68, 1,351.17 and 861.40

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Solution

The fourth proportional to 979.68, 1,351.17 and 861.40 is: 1,188.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.68 : 1,351.17 = 861.40 : x
  2. Step 2: Convert to fraction form
    979.68/1,351.17 = 861.40/x
  3. Step 3: Cross multiply
    979.68x = 1,351.17 × 861.40
  4. Step 4: Simplify right side
    979.68x = 1,163,897.84
  5. Step 5: Solve for x
    x = 1,163,897.84/979.68
  6. Step 6: Final answer
    x = 1,188.04

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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.