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Finding the Fourth Proportional to 1,138.78, 1,571.49 and 641.42

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Solution

The fourth proportional to 1,138.78, 1,571.49 and 641.42 is: 885.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.78 : 1,571.49 = 641.42 : x
  2. Step 2: Convert to fraction form
    1,138.78/1,571.49 = 641.42/x
  3. Step 3: Cross multiply
    1,138.78x = 1,571.49 × 641.42
  4. Step 4: Simplify right side
    1,138.78x = 1,007,974.05
  5. Step 5: Solve for x
    x = 1,007,974.05/1,138.78
  6. Step 6: Final answer
    x = 885.14

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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.