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Finding the Fourth Proportional to 675.78, 931.20 and 518.40

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Solution

The fourth proportional to 675.78, 931.20 and 518.40 is: 714.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    675.78 : 931.20 = 518.40 : x
  2. Step 2: Convert to fraction form
    675.78/931.20 = 518.40/x
  3. Step 3: Cross multiply
    675.78x = 931.20 × 518.40
  4. Step 4: Simplify right side
    675.78x = 482,734.08
  5. Step 5: Solve for x
    x = 482,734.08/675.78
  6. Step 6: Final answer
    x = 714.34

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.