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Finding the Fourth Proportional to 1,209.61, 1,669.43 and 678.70

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Solution

The fourth proportional to 1,209.61, 1,669.43 and 678.70 is: 936.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.61 : 1,669.43 = 678.70 : x
  2. Step 2: Convert to fraction form
    1,209.61/1,669.43 = 678.70/x
  3. Step 3: Cross multiply
    1,209.61x = 1,669.43 × 678.70
  4. Step 4: Simplify right side
    1,209.61x = 1,133,034.57
  5. Step 5: Solve for x
    x = 1,133,034.57/1,209.61
  6. Step 6: Final answer
    x = 936.70

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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.