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Finding the Fourth Proportional to 1,187.81, 1,780.15 and 859.85

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Solution

The fourth proportional to 1,187.81, 1,780.15 and 859.85 is: 1,288.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.81 : 1,780.15 = 859.85 : x
  2. Step 2: Convert to fraction form
    1,187.81/1,780.15 = 859.85/x
  3. Step 3: Cross multiply
    1,187.81x = 1,780.15 × 859.85
  4. Step 4: Simplify right side
    1,187.81x = 1,530,653.15
  5. Step 5: Solve for x
    x = 1,530,653.15/1,187.81
  6. Step 6: Final answer
    x = 1,288.63

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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.