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Finding the Fourth Proportional to 393.90, 543.78 and 305.18

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Solution

The fourth proportional to 393.90, 543.78 and 305.18 is: 421.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.90 : 543.78 = 305.18 : x
  2. Step 2: Convert to fraction form
    393.90/543.78 = 305.18/x
  3. Step 3: Cross multiply
    393.90x = 543.78 × 305.18
  4. Step 4: Simplify right side
    393.90x = 165,949.25
  5. Step 5: Solve for x
    x = 165,949.25/393.90
  6. Step 6: Final answer
    x = 421.30

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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.