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Finding the Fourth Proportional to 812.88, 1,123.20 and 639.54

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Solution

The fourth proportional to 812.88, 1,123.20 and 639.54 is: 883.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.88 : 1,123.20 = 639.54 : x
  2. Step 2: Convert to fraction form
    812.88/1,123.20 = 639.54/x
  3. Step 3: Cross multiply
    812.88x = 1,123.20 × 639.54
  4. Step 4: Simplify right side
    812.88x = 718,331.33
  5. Step 5: Solve for x
    x = 718,331.33/812.88
  6. Step 6: Final answer
    x = 883.69

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1.5x scale

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.