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Finding the Fourth Proportional to 642.64, 964.11 and 209.80

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Solution

The fourth proportional to 642.64, 964.11 and 209.80 is: 314.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.64 : 964.11 = 209.80 : x
  2. Step 2: Convert to fraction form
    642.64/964.11 = 209.80/x
  3. Step 3: Cross multiply
    642.64x = 964.11 × 209.80
  4. Step 4: Simplify right side
    642.64x = 202,270.28
  5. Step 5: Solve for x
    x = 202,270.28/642.64
  6. Step 6: Final answer
    x = 314.75

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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.