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Finding the Fourth Proportional to 699.43, 1,047.78 and 639.29

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Solution

The fourth proportional to 699.43, 1,047.78 and 639.29 is: 957.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    699.43 : 1,047.78 = 639.29 : x
  2. Step 2: Convert to fraction form
    699.43/1,047.78 = 639.29/x
  3. Step 3: Cross multiply
    699.43x = 1,047.78 × 639.29
  4. Step 4: Simplify right side
    699.43x = 669,826.84
  5. Step 5: Solve for x
    x = 669,826.84/699.43
  6. Step 6: Final answer
    x = 957.68

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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.