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Finding the Fourth Proportional to 678.09, 1,017.21 and 215.91

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Solution

The fourth proportional to 678.09, 1,017.21 and 215.91 is: 323.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.09 : 1,017.21 = 215.91 : x
  2. Step 2: Convert to fraction form
    678.09/1,017.21 = 215.91/x
  3. Step 3: Cross multiply
    678.09x = 1,017.21 × 215.91
  4. Step 4: Simplify right side
    678.09x = 219,625.81
  5. Step 5: Solve for x
    x = 219,625.81/678.09
  6. Step 6: Final answer
    x = 323.89

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.