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Finding the Fourth Proportional to 1,187.70, 1,639.90 and 768.30

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Solution

The fourth proportional to 1,187.70, 1,639.90 and 768.30 is: 1,060.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.70 : 1,639.90 = 768.30 : x
  2. Step 2: Convert to fraction form
    1,187.70/1,639.90 = 768.30/x
  3. Step 3: Cross multiply
    1,187.70x = 1,639.90 × 768.30
  4. Step 4: Simplify right side
    1,187.70x = 1,259,935.17
  5. Step 5: Solve for x
    x = 1,259,935.17/1,187.70
  6. Step 6: Final answer
    x = 1,060.82

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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.