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Finding the Fourth Proportional to 393.51, 542.85 and 305.57

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Solution

The fourth proportional to 393.51, 542.85 and 305.57 is: 421.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.51 : 542.85 = 305.57 : x
  2. Step 2: Convert to fraction form
    393.51/542.85 = 305.57/x
  3. Step 3: Cross multiply
    393.51x = 542.85 × 305.57
  4. Step 4: Simplify right side
    393.51x = 165,878.67
  5. Step 5: Solve for x
    x = 165,878.67/393.51
  6. Step 6: Final answer
    x = 421.54

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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.