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Finding the Fourth Proportional to 390.99, 539.40 and 243.57

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Solution

The fourth proportional to 390.99, 539.40 and 243.57 is: 336.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.99 : 539.40 = 243.57 : x
  2. Step 2: Convert to fraction form
    390.99/539.40 = 243.57/x
  3. Step 3: Cross multiply
    390.99x = 539.40 × 243.57
  4. Step 4: Simplify right side
    390.99x = 131,381.66
  5. Step 5: Solve for x
    x = 131,381.66/390.99
  6. Step 6: Final answer
    x = 336.02

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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.