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Finding the Fourth Proportional to 393.15, 542.43 and 309.99

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Solution

The fourth proportional to 393.15, 542.43 and 309.99 is: 427.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    393.15 : 542.43 = 309.99 : x
  2. Step 2: Convert to fraction form
    393.15/542.43 = 309.99/x
  3. Step 3: Cross multiply
    393.15x = 542.43 × 309.99
  4. Step 4: Simplify right side
    393.15x = 168,143.61
  5. Step 5: Solve for x
    x = 168,143.61/393.15
  6. Step 6: Final answer
    x = 427.69

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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.