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Finding the Fourth Proportional to 1,209.72, 1,669.49 and 678.65

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Solution

The fourth proportional to 1,209.72, 1,669.49 and 678.65 is: 936.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.72 : 1,669.49 = 678.65 : x
  2. Step 2: Convert to fraction form
    1,209.72/1,669.49 = 678.65/x
  3. Step 3: Cross multiply
    1,209.72x = 1,669.49 × 678.65
  4. Step 4: Simplify right side
    1,209.72x = 1,132,999.39
  5. Step 5: Solve for x
    x = 1,132,999.39/1,209.72
  6. Step 6: Final answer
    x = 936.58

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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.