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Finding the Fourth Proportional to 720.19, 1,080.39 and 257.88

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Solution

The fourth proportional to 720.19, 1,080.39 and 257.88 is: 386.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.19 : 1,080.39 = 257.88 : x
  2. Step 2: Convert to fraction form
    720.19/1,080.39 = 257.88/x
  3. Step 3: Cross multiply
    720.19x = 1,080.39 × 257.88
  4. Step 4: Simplify right side
    720.19x = 278,614.54
  5. Step 5: Solve for x
    x = 278,614.54/720.19
  6. Step 6: Final answer
    x = 386.86

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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.