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Finding the Fourth Proportional to 1,278.40, 1,917.78 and 653.92

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Solution

The fourth proportional to 1,278.40, 1,917.78 and 653.92 is: 980.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.40 : 1,917.78 = 653.92 : x
  2. Step 2: Convert to fraction form
    1,278.40/1,917.78 = 653.92/x
  3. Step 3: Cross multiply
    1,278.40x = 1,917.78 × 653.92
  4. Step 4: Simplify right side
    1,278.40x = 1,254,074.70
  5. Step 5: Solve for x
    x = 1,254,074.70/1,278.40
  6. Step 6: Final answer
    x = 980.97

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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.