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Finding the Fourth Proportional to 678.15, 1,017.20 and 191.21

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Solution

The fourth proportional to 678.15, 1,017.20 and 191.21 is: 286.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.15 : 1,017.20 = 191.21 : x
  2. Step 2: Convert to fraction form
    678.15/1,017.20 = 191.21/x
  3. Step 3: Cross multiply
    678.15x = 1,017.20 × 191.21
  4. Step 4: Simplify right side
    678.15x = 194,494.20
  5. Step 5: Solve for x
    x = 194,494.20/678.15
  6. Step 6: Final answer
    x = 286.80

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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.