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Finding the Fourth Proportional to 815.36, 1,221.66 and 643.14

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Solution

The fourth proportional to 815.36, 1,221.66 and 643.14 is: 963.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.36 : 1,221.66 = 643.14 : x
  2. Step 2: Convert to fraction form
    815.36/1,221.66 = 643.14/x
  3. Step 3: Cross multiply
    815.36x = 1,221.66 × 643.14
  4. Step 4: Simplify right side
    815.36x = 785,698.41
  5. Step 5: Solve for x
    x = 785,698.41/815.36
  6. Step 6: Final answer
    x = 963.63

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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.