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Finding the Fourth Proportional to 1,387.24, 2,080.78 and 839.28

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Solution

The fourth proportional to 1,387.24, 2,080.78 and 839.28 is: 1,258.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.24 : 2,080.78 = 839.28 : x
  2. Step 2: Convert to fraction form
    1,387.24/2,080.78 = 839.28/x
  3. Step 3: Cross multiply
    1,387.24x = 2,080.78 × 839.28
  4. Step 4: Simplify right side
    1,387.24x = 1,746,357.04
  5. Step 5: Solve for x
    x = 1,746,357.04/1,387.24
  6. Step 6: Final answer
    x = 1,258.87

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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.