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Finding the Fourth Proportional to 1,138.17, 1,570.54 and 640.78

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Solution

The fourth proportional to 1,138.17, 1,570.54 and 640.78 is: 884.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.17 : 1,570.54 = 640.78 : x
  2. Step 2: Convert to fraction form
    1,138.17/1,570.54 = 640.78/x
  3. Step 3: Cross multiply
    1,138.17x = 1,570.54 × 640.78
  4. Step 4: Simplify right side
    1,138.17x = 1,006,370.62
  5. Step 5: Solve for x
    x = 1,006,370.62/1,138.17
  6. Step 6: Final answer
    x = 884.20

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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.