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Finding the Fourth Proportional to 720.56, 1,080.90 and 258.40

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Solution

The fourth proportional to 720.56, 1,080.90 and 258.40 is: 387.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.56 : 1,080.90 = 258.40 : x
  2. Step 2: Convert to fraction form
    720.56/1,080.90 = 258.40/x
  3. Step 3: Cross multiply
    720.56x = 1,080.90 × 258.40
  4. Step 4: Simplify right side
    720.56x = 279,305.91
  5. Step 5: Solve for x
    x = 279,305.91/720.56
  6. Step 6: Final answer
    x = 387.62

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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.