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Finding the Fourth Proportional to 879.12, 1,213.20 and 480.78

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Solution

The fourth proportional to 879.12, 1,213.20 and 480.78 is: 663.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    879.12 : 1,213.20 = 480.78 : x
  2. Step 2: Convert to fraction form
    879.12/1,213.20 = 480.78/x
  3. Step 3: Cross multiply
    879.12x = 1,213.20 × 480.78
  4. Step 4: Simplify right side
    879.12x = 583,282.30
  5. Step 5: Solve for x
    x = 583,282.30/879.12
  6. Step 6: Final answer
    x = 663.48

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Double scale
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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.