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Finding the Fourth Proportional to 678.18, 1,015.65 and 388.74

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Solution

The fourth proportional to 678.18, 1,015.65 and 388.74 is: 582.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.18 : 1,015.65 = 388.74 : x
  2. Step 2: Convert to fraction form
    678.18/1,015.65 = 388.74/x
  3. Step 3: Cross multiply
    678.18x = 1,015.65 × 388.74
  4. Step 4: Simplify right side
    678.18x = 394,823.78
  5. Step 5: Solve for x
    x = 394,823.78/678.18
  6. Step 6: Final answer
    x = 582.18

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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.