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Finding the Fourth Proportional to 1,389.40, 1,917.52 and 800

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Solution

The fourth proportional to 1,389.40, 1,917.52 and 800 is: 1,104.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.40 : 1,917.52 = 800 : x
  2. Step 2: Convert to fraction form
    1,389.40/1,917.52 = 800/x
  3. Step 3: Cross multiply
    1,389.40x = 1,917.52 × 800
  4. Step 4: Simplify right side
    1,389.40x = 1,534,016
  5. Step 5: Solve for x
    x = 1,534,016/1,389.40
  6. Step 6: Final answer
    x = 1,104.09

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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.