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Finding the Fourth Proportional to 857.05, 1,278.67 and 815.74

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Solution

The fourth proportional to 857.05, 1,278.67 and 815.74 is: 1,217.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.05 : 1,278.67 = 815.74 : x
  2. Step 2: Convert to fraction form
    857.05/1,278.67 = 815.74/x
  3. Step 3: Cross multiply
    857.05x = 1,278.67 × 815.74
  4. Step 4: Simplify right side
    857.05x = 1,043,058.56
  5. Step 5: Solve for x
    x = 1,043,058.56/857.05
  6. Step 6: Final answer
    x = 1,217.04

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.