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Finding the Fourth Proportional to 699.40, 1,047.96 and 640.42

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Solution

The fourth proportional to 699.40, 1,047.96 and 640.42 is: 959.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    699.40 : 1,047.96 = 640.42 : x
  2. Step 2: Convert to fraction form
    699.40/1,047.96 = 640.42/x
  3. Step 3: Cross multiply
    699.40x = 1,047.96 × 640.42
  4. Step 4: Simplify right side
    699.40x = 671,134.54
  5. Step 5: Solve for x
    x = 671,134.54/699.40
  6. Step 6: Final answer
    x = 959.59

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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.