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Finding the Fourth Proportional to 1,191.80, 1,780.39 and 859.91

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Solution

The fourth proportional to 1,191.80, 1,780.39 and 859.91 is: 1,284.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,191.80 : 1,780.39 = 859.91 : x
  2. Step 2: Convert to fraction form
    1,191.80/1,780.39 = 859.91/x
  3. Step 3: Cross multiply
    1,191.80x = 1,780.39 × 859.91
  4. Step 4: Simplify right side
    1,191.80x = 1,530,975.16
  5. Step 5: Solve for x
    x = 1,530,975.16/1,191.80
  6. Step 6: Final answer
    x = 1,284.59

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.