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Finding the Fourth Proportional to 678.55, 1,018.13 and 345.31

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Solution

The fourth proportional to 678.55, 1,018.13 and 345.31 is: 518.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.55 : 1,018.13 = 345.31 : x
  2. Step 2: Convert to fraction form
    678.55/1,018.13 = 345.31/x
  3. Step 3: Cross multiply
    678.55x = 1,018.13 × 345.31
  4. Step 4: Simplify right side
    678.55x = 351,570.47
  5. Step 5: Solve for x
    x = 351,570.47/678.55
  6. Step 6: Final answer
    x = 518.12

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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.