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Finding the Fourth Proportional to 1,191.87, 1,786.59 and 643.91

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Solution

The fourth proportional to 1,191.87, 1,786.59 and 643.91 is: 965.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,191.87 : 1,786.59 = 643.91 : x
  2. Step 2: Convert to fraction form
    1,191.87/1,786.59 = 643.91/x
  3. Step 3: Cross multiply
    1,191.87x = 1,786.59 × 643.91
  4. Step 4: Simplify right side
    1,191.87x = 1,150,394.23
  5. Step 5: Solve for x
    x = 1,150,394.23/1,191.87
  6. Step 6: Final answer
    x = 965.20

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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.