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Finding the Fourth Proportional to 1,129.36, 1,557.79 and 815.43

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Solution

The fourth proportional to 1,129.36, 1,557.79 and 815.43 is: 1,124.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,129.36 : 1,557.79 = 815.43 : x
  2. Step 2: Convert to fraction form
    1,129.36/1,557.79 = 815.43/x
  3. Step 3: Cross multiply
    1,129.36x = 1,557.79 × 815.43
  4. Step 4: Simplify right side
    1,129.36x = 1,270,268.70
  5. Step 5: Solve for x
    x = 1,270,268.70/1,129.36
  6. Step 6: Final answer
    x = 1,124.77

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.