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Finding the Fourth Proportional to 1,138.12, 1,570.20 and 640.68

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Solution

The fourth proportional to 1,138.12, 1,570.20 and 640.68 is: 883.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.12 : 1,570.20 = 640.68 : x
  2. Step 2: Convert to fraction form
    1,138.12/1,570.20 = 640.68/x
  3. Step 3: Cross multiply
    1,138.12x = 1,570.20 × 640.68
  4. Step 4: Simplify right side
    1,138.12x = 1,005,995.74
  5. Step 5: Solve for x
    x = 1,005,995.74/1,138.12
  6. Step 6: Final answer
    x = 883.91

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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.