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Finding the Fourth Proportional to 678.25, 1,015.39 and 613.40

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Solution

The fourth proportional to 678.25, 1,015.39 and 613.40 is: 918.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.25 : 1,015.39 = 613.40 : x
  2. Step 2: Convert to fraction form
    678.25/1,015.39 = 613.40/x
  3. Step 3: Cross multiply
    678.25x = 1,015.39 × 613.40
  4. Step 4: Simplify right side
    678.25x = 622,832.08
  5. Step 5: Solve for x
    x = 622,832.08/678.25
  6. Step 6: Final answer
    x = 918.30

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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.