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Finding the Fourth Proportional to 1,785.78, 2,678.61 and 811.20

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Solution

The fourth proportional to 1,785.78, 2,678.61 and 811.20 is: 1,216.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,785.78 : 2,678.61 = 811.20 : x
  2. Step 2: Convert to fraction form
    1,785.78/2,678.61 = 811.20/x
  3. Step 3: Cross multiply
    1,785.78x = 2,678.61 × 811.20
  4. Step 4: Simplify right side
    1,785.78x = 2,172,888.43
  5. Step 5: Solve for x
    x = 2,172,888.43/1,785.78
  6. Step 6: Final answer
    x = 1,216.77

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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.