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Finding the Fourth Proportional to 678.56, 1,017.00 and 386.31

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Solution

The fourth proportional to 678.56, 1,017.00 and 386.31 is: 578.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.56 : 1,017.00 = 386.31 : x
  2. Step 2: Convert to fraction form
    678.56/1,017.00 = 386.31/x
  3. Step 3: Cross multiply
    678.56x = 1,017.00 × 386.31
  4. Step 4: Simplify right side
    678.56x = 392,873.15
  5. Step 5: Solve for x
    x = 392,873.15/678.56
  6. Step 6: Final answer
    x = 578.98

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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.