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Finding the Fourth Proportional to 821.49, 1,229.95 and 639.24

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Solution

The fourth proportional to 821.49, 1,229.95 and 639.24 is: 957.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.49 : 1,229.95 = 639.24 : x
  2. Step 2: Convert to fraction form
    821.49/1,229.95 = 639.24/x
  3. Step 3: Cross multiply
    821.49x = 1,229.95 × 639.24
  4. Step 4: Simplify right side
    821.49x = 786,231.64
  5. Step 5: Solve for x
    x = 786,231.64/821.49
  6. Step 6: Final answer
    x = 957.08

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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.