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Finding the Fourth Proportional to 642.75, 964.20 and 209.91

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Solution

The fourth proportional to 642.75, 964.20 and 209.91 is: 314.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.75 : 964.20 = 209.91 : x
  2. Step 2: Convert to fraction form
    642.75/964.20 = 209.91/x
  3. Step 3: Cross multiply
    642.75x = 964.20 × 209.91
  4. Step 4: Simplify right side
    642.75x = 202,395.22
  5. Step 5: Solve for x
    x = 202,395.22/642.75
  6. Step 6: Final answer
    x = 314.89

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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.