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Finding the Fourth Proportional to 678.75, 1,018.11 and 191.80

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Solution

The fourth proportional to 678.75, 1,018.11 and 191.80 is: 287.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.75 : 1,018.11 = 191.80 : x
  2. Step 2: Convert to fraction form
    678.75/1,018.11 = 191.80/x
  3. Step 3: Cross multiply
    678.75x = 1,018.11 × 191.80
  4. Step 4: Simplify right side
    678.75x = 195,275.49
  5. Step 5: Solve for x
    x = 195,275.49/678.75
  6. Step 6: Final answer
    x = 287.70

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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.