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Finding the Fourth Proportional to 981.76, 1,471.76 and 721.12

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Solution

The fourth proportional to 981.76, 1,471.76 and 721.12 is: 1,081.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.76 : 1,471.76 = 721.12 : x
  2. Step 2: Convert to fraction form
    981.76/1,471.76 = 721.12/x
  3. Step 3: Cross multiply
    981.76x = 1,471.76 × 721.12
  4. Step 4: Simplify right side
    981.76x = 1,061,315.57
  5. Step 5: Solve for x
    x = 1,061,315.57/981.76
  6. Step 6: Final answer
    x = 1,081.03

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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.