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Finding the Fourth Proportional to 1,209.74, 1,669.55 and 678.71

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Solution

The fourth proportional to 1,209.74, 1,669.55 and 678.71 is: 936.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.74 : 1,669.55 = 678.71 : x
  2. Step 2: Convert to fraction form
    1,209.74/1,669.55 = 678.71/x
  3. Step 3: Cross multiply
    1,209.74x = 1,669.55 × 678.71
  4. Step 4: Simplify right side
    1,209.74x = 1,133,141.06
  5. Step 5: Solve for x
    x = 1,133,141.06/1,209.74
  6. Step 6: Final answer
    x = 936.69

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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.