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Finding the Fourth Proportional to 678.20, 1,016.69 and 312.75

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Solution

The fourth proportional to 678.20, 1,016.69 and 312.75 is: 468.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.20 : 1,016.69 = 312.75 : x
  2. Step 2: Convert to fraction form
    678.20/1,016.69 = 312.75/x
  3. Step 3: Cross multiply
    678.20x = 1,016.69 × 312.75
  4. Step 4: Simplify right side
    678.20x = 317,968.23
  5. Step 5: Solve for x
    x = 317,968.23/678.20
  6. Step 6: Final answer
    x = 468.84

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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.