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Finding the Fourth Proportional to 1,279.43, 1,917.30 and 661.80

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Solution

The fourth proportional to 1,279.43, 1,917.30 and 661.80 is: 991.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,279.43 : 1,917.30 = 661.80 : x
  2. Step 2: Convert to fraction form
    1,279.43/1,917.30 = 661.80/x
  3. Step 3: Cross multiply
    1,279.43x = 1,917.30 × 661.80
  4. Step 4: Simplify right side
    1,279.43x = 1,268,878.81
  5. Step 5: Solve for x
    x = 1,268,878.81/1,279.43
  6. Step 6: Final answer
    x = 991.75

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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.