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Finding the Fourth Proportional to 815.02, 1,220.80 and 640.86

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Solution

The fourth proportional to 815.02, 1,220.80 and 640.86 is: 959.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.02 : 1,220.80 = 640.86 : x
  2. Step 2: Convert to fraction form
    815.02/1,220.80 = 640.86/x
  3. Step 3: Cross multiply
    815.02x = 1,220.80 × 640.86
  4. Step 4: Simplify right side
    815.02x = 782,361.89
  5. Step 5: Solve for x
    x = 782,361.89/815.02
  6. Step 6: Final answer
    x = 959.93

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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.