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Finding the Fourth Proportional to 678.12, 1,015.82 and 312.40

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Solution

The fourth proportional to 678.12, 1,015.82 and 312.40 is: 467.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.12 : 1,015.82 = 312.40 : x
  2. Step 2: Convert to fraction form
    678.12/1,015.82 = 312.40/x
  3. Step 3: Cross multiply
    678.12x = 1,015.82 × 312.40
  4. Step 4: Simplify right side
    678.12x = 317,342.17
  5. Step 5: Solve for x
    x = 317,342.17/678.12
  6. Step 6: Final answer
    x = 467.97

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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.