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Finding the Fourth Proportional to 698.40, 1,040.64 and 621.78

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Solution

The fourth proportional to 698.40, 1,040.64 and 621.78 is: 926.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    698.40 : 1,040.64 = 621.78 : x
  2. Step 2: Convert to fraction form
    698.40/1,040.64 = 621.78/x
  3. Step 3: Cross multiply
    698.40x = 1,040.64 × 621.78
  4. Step 4: Simplify right side
    698.40x = 647,049.14
  5. Step 5: Solve for x
    x = 647,049.14/698.40
  6. Step 6: Final answer
    x = 926.47

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.