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Finding the Fourth Proportional to 421.64, 634.78 and 388.16

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Solution

The fourth proportional to 421.64, 634.78 and 388.16 is: 584.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.64 : 634.78 = 388.16 : x
  2. Step 2: Convert to fraction form
    421.64/634.78 = 388.16/x
  3. Step 3: Cross multiply
    421.64x = 634.78 × 388.16
  4. Step 4: Simplify right side
    421.64x = 246,396.20
  5. Step 5: Solve for x
    x = 246,396.20/421.64
  6. Step 6: Final answer
    x = 584.38

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.