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Finding the Fourth Proportional to 678.36, 1,017.60 and 191.40

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Solution

The fourth proportional to 678.36, 1,017.60 and 191.40 is: 287.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.36 : 1,017.60 = 191.40 : x
  2. Step 2: Convert to fraction form
    678.36/1,017.60 = 191.40/x
  3. Step 3: Cross multiply
    678.36x = 1,017.60 × 191.40
  4. Step 4: Simplify right side
    678.36x = 194,768.64
  5. Step 5: Solve for x
    x = 194,768.64/678.36
  6. Step 6: Final answer
    x = 287.12

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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.