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Finding the Fourth Proportional to 720.79, 1,081.14 and 258.55

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Solution

The fourth proportional to 720.79, 1,081.14 and 258.55 is: 387.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.79 : 1,081.14 = 258.55 : x
  2. Step 2: Convert to fraction form
    720.79/1,081.14 = 258.55/x
  3. Step 3: Cross multiply
    720.79x = 1,081.14 × 258.55
  4. Step 4: Simplify right side
    720.79x = 279,531.16
  5. Step 5: Solve for x
    x = 279,531.16/720.79
  6. Step 6: Final answer
    x = 387.81

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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.