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Finding the Fourth Proportional to 1,278.68, 1,915 and 839.66

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Solution

The fourth proportional to 1,278.68, 1,915 and 839.66 is: 1,257.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.68 : 1,915 = 839.66 : x
  2. Step 2: Convert to fraction form
    1,278.68/1,915 = 839.66/x
  3. Step 3: Cross multiply
    1,278.68x = 1,915 × 839.66
  4. Step 4: Simplify right side
    1,278.68x = 1,607,948.90
  5. Step 5: Solve for x
    x = 1,607,948.90/1,278.68
  6. Step 6: Final answer
    x = 1,257.51

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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.