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Finding the Fourth Proportional to 678.61, 1,017.39 and 312.96

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Solution

The fourth proportional to 678.61, 1,017.39 and 312.96 is: 469.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.61 : 1,017.39 = 312.96 : x
  2. Step 2: Convert to fraction form
    678.61/1,017.39 = 312.96/x
  3. Step 3: Cross multiply
    678.61x = 1,017.39 × 312.96
  4. Step 4: Simplify right side
    678.61x = 318,402.37
  5. Step 5: Solve for x
    x = 318,402.37/678.61
  6. Step 6: Final answer
    x = 469.20

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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.