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Finding the Fourth Proportional to 720.55, 1,081.08 and 258.40

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Solution

The fourth proportional to 720.55, 1,081.08 and 258.40 is: 387.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.55 : 1,081.08 = 258.40 : x
  2. Step 2: Convert to fraction form
    720.55/1,081.08 = 258.40/x
  3. Step 3: Cross multiply
    720.55x = 1,081.08 × 258.40
  4. Step 4: Simplify right side
    720.55x = 279,351.07
  5. Step 5: Solve for x
    x = 279,351.07/720.55
  6. Step 6: Final answer
    x = 387.69

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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.