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Finding the Fourth Proportional to 1,278.76, 1,919.78 and 869.72

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Solution

The fourth proportional to 1,278.76, 1,919.78 and 869.72 is: 1,305.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.76 : 1,919.78 = 869.72 : x
  2. Step 2: Convert to fraction form
    1,278.76/1,919.78 = 869.72/x
  3. Step 3: Cross multiply
    1,278.76x = 1,919.78 × 869.72
  4. Step 4: Simplify right side
    1,278.76x = 1,669,671.06
  5. Step 5: Solve for x
    x = 1,669,671.06/1,278.76
  6. Step 6: Final answer
    x = 1,305.70

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1.5x scale

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.