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Finding the Fourth Proportional to 815.32, 1,219.63 and 678.55

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Solution

The fourth proportional to 815.32, 1,219.63 and 678.55 is: 1,015.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.32 : 1,219.63 = 678.55 : x
  2. Step 2: Convert to fraction form
    815.32/1,219.63 = 678.55/x
  3. Step 3: Cross multiply
    815.32x = 1,219.63 × 678.55
  4. Step 4: Simplify right side
    815.32x = 827,579.94
  5. Step 5: Solve for x
    x = 827,579.94/815.32
  6. Step 6: Final answer
    x = 1,015.04

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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.