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Finding the Fourth Proportional to 815.10, 1,219.92 and 678.42

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Solution

The fourth proportional to 815.10, 1,219.92 and 678.42 is: 1,015.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.10 : 1,219.92 = 678.42 : x
  2. Step 2: Convert to fraction form
    815.10/1,219.92 = 678.42/x
  3. Step 3: Cross multiply
    815.10x = 1,219.92 × 678.42
  4. Step 4: Simplify right side
    815.10x = 827,618.13
  5. Step 5: Solve for x
    x = 827,618.13/815.10
  6. Step 6: Final answer
    x = 1,015.36

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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.