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Finding the Fourth Proportional to 678.12, 1,017.30 and 645.36

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Solution

The fourth proportional to 678.12, 1,017.30 and 645.36 is: 968.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.12 : 1,017.30 = 645.36 : x
  2. Step 2: Convert to fraction form
    678.12/1,017.30 = 645.36/x
  3. Step 3: Cross multiply
    678.12x = 1,017.30 × 645.36
  4. Step 4: Simplify right side
    678.12x = 656,524.73
  5. Step 5: Solve for x
    x = 656,524.73/678.12
  6. Step 6: Final answer
    x = 968.15

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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.