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Finding the Fourth Proportional to 720.15, 1,080 and 257.87

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Solution

The fourth proportional to 720.15, 1,080 and 257.87 is: 386.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.15 : 1,080 = 257.87 : x
  2. Step 2: Convert to fraction form
    720.15/1,080 = 257.87/x
  3. Step 3: Cross multiply
    720.15x = 1,080 × 257.87
  4. Step 4: Simplify right side
    720.15x = 278,499.60
  5. Step 5: Solve for x
    x = 278,499.60/720.15
  6. Step 6: Final answer
    x = 386.72

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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.