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Finding the Fourth Proportional to 1,187.71, 1,640.13 and 768.79

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Solution

The fourth proportional to 1,187.71, 1,640.13 and 768.79 is: 1,061.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.71 : 1,640.13 = 768.79 : x
  2. Step 2: Convert to fraction form
    1,187.71/1,640.13 = 768.79/x
  3. Step 3: Cross multiply
    1,187.71x = 1,640.13 × 768.79
  4. Step 4: Simplify right side
    1,187.71x = 1,260,911.44
  5. Step 5: Solve for x
    x = 1,260,911.44/1,187.71
  6. Step 6: Final answer
    x = 1,061.63

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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.