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Finding the Fourth Proportional to 812.20, 1,120.47 and 638.05

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Solution

The fourth proportional to 812.20, 1,120.47 and 638.05 is: 880.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.20 : 1,120.47 = 638.05 : x
  2. Step 2: Convert to fraction form
    812.20/1,120.47 = 638.05/x
  3. Step 3: Cross multiply
    812.20x = 1,120.47 × 638.05
  4. Step 4: Simplify right side
    812.20x = 714,910.28
  5. Step 5: Solve for x
    x = 714,910.28/812.20
  6. Step 6: Final answer
    x = 880.22

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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.