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Finding the Fourth Proportional to 815.88, 1,223.50 and 642.88

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Solution

The fourth proportional to 815.88, 1,223.50 and 642.88 is: 964.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.88 : 1,223.50 = 642.88 : x
  2. Step 2: Convert to fraction form
    815.88/1,223.50 = 642.88/x
  3. Step 3: Cross multiply
    815.88x = 1,223.50 × 642.88
  4. Step 4: Simplify right side
    815.88x = 786,563.68
  5. Step 5: Solve for x
    x = 786,563.68/815.88
  6. Step 6: Final answer
    x = 964.07

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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.