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Finding the Fourth Proportional to 721.10, 1,080.78 and 611.08

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Solution

The fourth proportional to 721.10, 1,080.78 and 611.08 is: 915.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.10 : 1,080.78 = 611.08 : x
  2. Step 2: Convert to fraction form
    721.10/1,080.78 = 611.08/x
  3. Step 3: Cross multiply
    721.10x = 1,080.78 × 611.08
  4. Step 4: Simplify right side
    721.10x = 660,438.05
  5. Step 5: Solve for x
    x = 660,438.05/721.10
  6. Step 6: Final answer
    x = 915.87

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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.