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Finding the Fourth Proportional to 815.67, 1,221.21 and 611.19

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Solution

The fourth proportional to 815.67, 1,221.21 and 611.19 is: 915.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.67 : 1,221.21 = 611.19 : x
  2. Step 2: Convert to fraction form
    815.67/1,221.21 = 611.19/x
  3. Step 3: Cross multiply
    815.67x = 1,221.21 × 611.19
  4. Step 4: Simplify right side
    815.67x = 746,391.34
  5. Step 5: Solve for x
    x = 746,391.34/815.67
  6. Step 6: Final answer
    x = 915.07

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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.