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Finding the Fourth Proportional to 678.28, 1,017.31 and 312.99

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Solution

The fourth proportional to 678.28, 1,017.31 and 312.99 is: 469.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.28 : 1,017.31 = 312.99 : x
  2. Step 2: Convert to fraction form
    678.28/1,017.31 = 312.99/x
  3. Step 3: Cross multiply
    678.28x = 1,017.31 × 312.99
  4. Step 4: Simplify right side
    678.28x = 318,407.86
  5. Step 5: Solve for x
    x = 318,407.86/678.28
  6. Step 6: Final answer
    x = 469.43

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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.