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Finding the Fourth Proportional to 815.50, 1,121.52 and 647.74

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Solution

The fourth proportional to 815.50, 1,121.52 and 647.74 is: 890.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.50 : 1,121.52 = 647.74 : x
  2. Step 2: Convert to fraction form
    815.50/1,121.52 = 647.74/x
  3. Step 3: Cross multiply
    815.50x = 1,121.52 × 647.74
  4. Step 4: Simplify right side
    815.50x = 726,453.36
  5. Step 5: Solve for x
    x = 726,453.36/815.50
  6. Step 6: Final answer
    x = 890.81

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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.