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Finding the Fourth Proportional to 1,311.32, 1,811.61 and 979.17

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Solution

The fourth proportional to 1,311.32, 1,811.61 and 979.17 is: 1,352.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.32 : 1,811.61 = 979.17 : x
  2. Step 2: Convert to fraction form
    1,311.32/1,811.61 = 979.17/x
  3. Step 3: Cross multiply
    1,311.32x = 1,811.61 × 979.17
  4. Step 4: Simplify right side
    1,311.32x = 1,773,874.16
  5. Step 5: Solve for x
    x = 1,773,874.16/1,311.32
  6. Step 6: Final answer
    x = 1,352.74

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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.