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Finding the Fourth Proportional to 1,338.80, 2,009.64 and 689.36

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Solution

The fourth proportional to 1,338.80, 2,009.64 and 689.36 is: 1,034.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,338.80 : 2,009.64 = 689.36 : x
  2. Step 2: Convert to fraction form
    1,338.80/2,009.64 = 689.36/x
  3. Step 3: Cross multiply
    1,338.80x = 2,009.64 × 689.36
  4. Step 4: Simplify right side
    1,338.80x = 1,385,365.43
  5. Step 5: Solve for x
    x = 1,385,365.43/1,338.80
  6. Step 6: Final answer
    x = 1,034.78

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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.