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Finding the Fourth Proportional to 721.56, 1,079.91 and 661.62

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Solution

The fourth proportional to 721.56, 1,079.91 and 661.62 is: 990.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.56 : 1,079.91 = 661.62 : x
  2. Step 2: Convert to fraction form
    721.56/1,079.91 = 661.62/x
  3. Step 3: Cross multiply
    721.56x = 1,079.91 × 661.62
  4. Step 4: Simplify right side
    721.56x = 714,490.05
  5. Step 5: Solve for x
    x = 714,490.05/721.56
  6. Step 6: Final answer
    x = 990.20

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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.