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Finding the Fourth Proportional to 811.79, 1,217.99 and 721.17

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Solution

The fourth proportional to 811.79, 1,217.99 and 721.17 is: 1,082.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.79 : 1,217.99 = 721.17 : x
  2. Step 2: Convert to fraction form
    811.79/1,217.99 = 721.17/x
  3. Step 3: Cross multiply
    811.79x = 1,217.99 × 721.17
  4. Step 4: Simplify right side
    811.79x = 878,374.24
  5. Step 5: Solve for x
    x = 878,374.24/811.79
  6. Step 6: Final answer
    x = 1,082.03

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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.