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Finding the Fourth Proportional to 721.40, 1,081.86 and 259.10

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Solution

The fourth proportional to 721.40, 1,081.86 and 259.10 is: 388.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.40 : 1,081.86 = 259.10 : x
  2. Step 2: Convert to fraction form
    721.40/1,081.86 = 259.10/x
  3. Step 3: Cross multiply
    721.40x = 1,081.86 × 259.10
  4. Step 4: Simplify right side
    721.40x = 280,309.93
  5. Step 5: Solve for x
    x = 280,309.93/721.40
  6. Step 6: Final answer
    x = 388.56

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Double scale
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Similar ratio
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1.5x scale

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.