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Finding the Fourth Proportional to 1,278.84, 1,765.08 and 813

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Solution

The fourth proportional to 1,278.84, 1,765.08 and 813 is: 1,122.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.84 : 1,765.08 = 813 : x
  2. Step 2: Convert to fraction form
    1,278.84/1,765.08 = 813/x
  3. Step 3: Cross multiply
    1,278.84x = 1,765.08 × 813
  4. Step 4: Simplify right side
    1,278.84x = 1,435,010.04
  5. Step 5: Solve for x
    x = 1,435,010.04/1,278.84
  6. Step 6: Final answer
    x = 1,122.12

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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.