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Finding the Fourth Proportional to 786.39, 1,178.78 and 439.31

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Solution

The fourth proportional to 786.39, 1,178.78 and 439.31 is: 658.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.39 : 1,178.78 = 439.31 : x
  2. Step 2: Convert to fraction form
    786.39/1,178.78 = 439.31/x
  3. Step 3: Cross multiply
    786.39x = 1,178.78 × 439.31
  4. Step 4: Simplify right side
    786.39x = 517,841.75
  5. Step 5: Solve for x
    x = 517,841.75/786.39
  6. Step 6: Final answer
    x = 658.51

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Double scale
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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.