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Finding the Fourth Proportional to 1,291.20, 1,781.97 and 786.99

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Solution

The fourth proportional to 1,291.20, 1,781.97 and 786.99 is: 1,086.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.20 : 1,781.97 = 786.99 : x
  2. Step 2: Convert to fraction form
    1,291.20/1,781.97 = 786.99/x
  3. Step 3: Cross multiply
    1,291.20x = 1,781.97 × 786.99
  4. Step 4: Simplify right side
    1,291.20x = 1,402,392.57
  5. Step 5: Solve for x
    x = 1,402,392.57/1,291.20
  6. Step 6: Final answer
    x = 1,086.12

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.