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Finding the Fourth Proportional to 1,138.57, 1,571.20 and 641.20

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Solution

The fourth proportional to 1,138.57, 1,571.20 and 641.20 is: 884.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.57 : 1,571.20 = 641.20 : x
  2. Step 2: Convert to fraction form
    1,138.57/1,571.20 = 641.20/x
  3. Step 3: Cross multiply
    1,138.57x = 1,571.20 × 641.20
  4. Step 4: Simplify right side
    1,138.57x = 1,007,442.38
  5. Step 5: Solve for x
    x = 1,007,442.38/1,138.57
  6. Step 6: Final answer
    x = 884.84

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Half scale
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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.