Home / 1,387.14-1,909.39-1,209.78

Finding the Fourth Proportional to 1,387.14, 1,909.39 and 1,209.78

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Solution

The fourth proportional to 1,387.14, 1,909.39 and 1,209.78 is: 1,665.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.14 : 1,909.39 = 1,209.78 : x
  2. Step 2: Convert to fraction form
    1,387.14/1,909.39 = 1,209.78/x
  3. Step 3: Cross multiply
    1,387.14x = 1,909.39 × 1,209.78
  4. Step 4: Simplify right side
    1,387.14x = 2,309,942.29
  5. Step 5: Solve for x
    x = 2,309,942.29/1,387.14
  6. Step 6: Final answer
    x = 1,665.25

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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.