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Finding the Fourth Proportional to 1,209.65, 1,669.39 and 678.57

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Solution

The fourth proportional to 1,209.65, 1,669.39 and 678.57 is: 936.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.65 : 1,669.39 = 678.57 : x
  2. Step 2: Convert to fraction form
    1,209.65/1,669.39 = 678.57/x
  3. Step 3: Cross multiply
    1,209.65x = 1,669.39 × 678.57
  4. Step 4: Simplify right side
    1,209.65x = 1,132,790.02
  5. Step 5: Solve for x
    x = 1,132,790.02/1,209.65
  6. Step 6: Final answer
    x = 936.46

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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.