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Finding the Fourth Proportional to 1,087.45, 1,631.19 and 781.90

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Solution

The fourth proportional to 1,087.45, 1,631.19 and 781.90 is: 1,172.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,087.45 : 1,631.19 = 781.90 : x
  2. Step 2: Convert to fraction form
    1,087.45/1,631.19 = 781.90/x
  3. Step 3: Cross multiply
    1,087.45x = 1,631.19 × 781.90
  4. Step 4: Simplify right side
    1,087.45x = 1,275,427.46
  5. Step 5: Solve for x
    x = 1,275,427.46/1,087.45
  6. Step 6: Final answer
    x = 1,172.86

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.