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Finding the Fourth Proportional to 678.10, 1,017.12 and 191.20

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Solution

The fourth proportional to 678.10, 1,017.12 and 191.20 is: 286.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.10 : 1,017.12 = 191.20 : x
  2. Step 2: Convert to fraction form
    678.10/1,017.12 = 191.20/x
  3. Step 3: Cross multiply
    678.10x = 1,017.12 × 191.20
  4. Step 4: Simplify right side
    678.10x = 194,473.34
  5. Step 5: Solve for x
    x = 194,473.34/678.10
  6. Step 6: Final answer
    x = 286.79

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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.