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Finding the Fourth Proportional to 678.45, 1,017.81 and 386.10

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Solution

The fourth proportional to 678.45, 1,017.81 and 386.10 is: 579.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.45 : 1,017.81 = 386.10 : x
  2. Step 2: Convert to fraction form
    678.45/1,017.81 = 386.10/x
  3. Step 3: Cross multiply
    678.45x = 1,017.81 × 386.10
  4. Step 4: Simplify right side
    678.45x = 392,976.44
  5. Step 5: Solve for x
    x = 392,976.44/678.45
  6. Step 6: Final answer
    x = 579.23

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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.