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Finding the Fourth Proportional to 865.70, 1,298.79 and 378.86

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Solution

The fourth proportional to 865.70, 1,298.79 and 378.86 is: 568.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.70 : 1,298.79 = 378.86 : x
  2. Step 2: Convert to fraction form
    865.70/1,298.79 = 378.86/x
  3. Step 3: Cross multiply
    865.70x = 1,298.79 × 378.86
  4. Step 4: Simplify right side
    865.70x = 492,059.58
  5. Step 5: Solve for x
    x = 492,059.58/865.70
  6. Step 6: Final answer
    x = 568.40

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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.