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Finding the Fourth Proportional to 1,209.78, 1,669.62 and 685.92

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Solution

The fourth proportional to 1,209.78, 1,669.62 and 685.92 is: 946.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.78 : 1,669.62 = 685.92 : x
  2. Step 2: Convert to fraction form
    1,209.78/1,669.62 = 685.92/x
  3. Step 3: Cross multiply
    1,209.78x = 1,669.62 × 685.92
  4. Step 4: Simplify right side
    1,209.78x = 1,145,225.75
  5. Step 5: Solve for x
    x = 1,145,225.75/1,209.78
  6. Step 6: Final answer
    x = 946.64

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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.