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Finding the Fourth Proportional to 1,291.19, 1,781.78 and 731.66

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Solution

The fourth proportional to 1,291.19, 1,781.78 and 731.66 is: 1,009.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.19 : 1,781.78 = 731.66 : x
  2. Step 2: Convert to fraction form
    1,291.19/1,781.78 = 731.66/x
  3. Step 3: Cross multiply
    1,291.19x = 1,781.78 × 731.66
  4. Step 4: Simplify right side
    1,291.19x = 1,303,644.59
  5. Step 5: Solve for x
    x = 1,303,644.59/1,291.19
  6. Step 6: Final answer
    x = 1,009.65

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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.