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Finding the Fourth Proportional to 815.40, 1,226.70 and 764.28

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Solution

The fourth proportional to 815.40, 1,226.70 and 764.28 is: 1,149.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.40 : 1,226.70 = 764.28 : x
  2. Step 2: Convert to fraction form
    815.40/1,226.70 = 764.28/x
  3. Step 3: Cross multiply
    815.40x = 1,226.70 × 764.28
  4. Step 4: Simplify right side
    815.40x = 937,542.28
  5. Step 5: Solve for x
    x = 937,542.28/815.40
  6. Step 6: Final answer
    x = 1,149.79

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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.