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Finding the Fourth Proportional to 393.12, 542.34 and 305.64

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Solution

The fourth proportional to 393.12, 542.34 and 305.64 is: 421.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.12 : 542.34 = 305.64 : x
  2. Step 2: Convert to fraction form
    393.12/542.34 = 305.64/x
  3. Step 3: Cross multiply
    393.12x = 542.34 × 305.64
  4. Step 4: Simplify right side
    393.12x = 165,760.80
  5. Step 5: Solve for x
    x = 165,760.80/393.12
  6. Step 6: Final answer
    x = 421.65

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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.